Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical defin...Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical definition of the ratio of the internal pressure/stress to the volume strain. Under various conditions, the bulk moduli obtained agree with the previous theoretical derivations from completely different approaches. It is found that the bulk moduli of2D Yukawa solids and liquids are almost independent of the system temperature and the external compressional frequency.展开更多
Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with recons...Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.展开更多
InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hinder...InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces.In this study,we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering.We engineered an InSe/h-BN heterostructure,effectively suppressing dielectric layer-induced scattering.Additionally,we successfully established excellent metal-semiconductor contacts using graphene ribbons as a buffer layer.Through a methodical approach to interface engineering,our graphene/InSe/h-BN transistor demonstrates impressive on-state current,field-effect mobility,and on/off ratio at room temperature,reaching values as high as 1.1 mA/μm,904 cm^(2)·V^(-1)·s^(-1),and>10~6,respectively.Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction,contributing to the enhanced performance of InSe transistors.This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors,paving the way for their utilization in future electronic applications.展开更多
Fractional molecular field theory(FMFT)is a phenomenological theory that describes phase transitions in crystals with randomly distributed components,such as the relaxor-ferroelectrics and spin glasses.In order to ver...Fractional molecular field theory(FMFT)is a phenomenological theory that describes phase transitions in crystals with randomly distributed components,such as the relaxor-ferroelectrics and spin glasses.In order to verify the feasibility of this theory,this paper fits it to the Monte Carlo simulations of specific heat and susceptibility versus temperature of two-dimensional(2D)random-site Ising model(2D-RSIM).The results indicate that the FMFT deviates from the 2D-RSIM significantly.The main reason for the deviation is that the 2D-RSIM is a typical system of component random distribution,where the real order parameter is spatially heterogeneous and has no symmetry of space translation,but the basic assumption of FMFT means that the parameter is spatially uniform and has symmetry of space translation.展开更多
Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the ort...Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM modes.In this paper,we propose a novel OAM hologram generation method based on a densely connected U-net(DCU),where the densely connected convolution blocks(DCB)replace the convolution blocks of the U-net.Importantly,the reconstruction process of the OAM hologram is integrated into DCU as its output layer,so as to eliminate the requirement to prepare training data for the OAM hologram,which is required by conventional neural networks through an iterative algorithm.The experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU,and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method,the Gerchberg-Saxton based generation method and the U-net method.In addition,a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram.展开更多
By utilizing the fluctuation exchange approximation method,we perform a study on the superconducting pairing symmetry in a t_(2g) three-orbital model on the square lattice.Although the tight-binding parameters of the ...By utilizing the fluctuation exchange approximation method,we perform a study on the superconducting pairing symmetry in a t_(2g) three-orbital model on the square lattice.Although the tight-binding parameters of the model are based on Sr_(2)RuO_(4),we have systematically studied the evolution of superconducting pairing symmetry with the carrier density and interactions,making our findings relevant to a broader range of material systems.Under a moderate Hund’s coupling,we find that spin fluctuations dominate the superconducting pairing,leading to a prevalent spin-singlet pairing with a d_(x^(2)-y^(2))-wave symmetry for the carrier density within the range of n=1.5-4 per site.By reducing the Hund’s coupling,the charge fluctuations are enhanced and play a crucial role in determining the pairing symmetry,leading to a transition of the pairing symmetry from the spin-singlet d_(x^(2)-y^(2))-wave to the spin-triplet p-wave.Furthermore,we find that the superconducting pairings are orbital dependent.As the carrier density changes from n=4 to n=1.5,the active orbitals for superconducting pairing shift from the quasi-two-dimensional orbital dxy to the quasi-one-dimensional orbitals d_(xz) and d_(yz).展开更多
We analyze the properties of a focused Laguerre–Gaussian(LG)beam propagating through anisotropic ocean turbulence based on the Huygens–Fresnel principle.Under the Rytov approximation theory,we derive the analytical ...We analyze the properties of a focused Laguerre–Gaussian(LG)beam propagating through anisotropic ocean turbulence based on the Huygens–Fresnel principle.Under the Rytov approximation theory,we derive the analytical formula of the channel capacity of the focused LG beam in the anisotropic ocean turbulence,and analyze the relationship between the capacity and the light source parameters as well as the turbulent ocean parameters.It is found that the focusing mirror can greatly enhance the channel capacity of the system at the geometric focal plane in oceanic turbulence.The results also demonstrate that the communication link can obtain high channel capacity by adopting longer beam wavelength,greater initial beam waist radius,and larger number of transmission channels.Further,the capacity of the system increases with the decrease of the mean squared temperature dissipation rate,temperature-salinity contribution ratio and turbulence outer scale factor,and with the increase of the kinetic energy dissipation rate per unit mass of fluid,turbulence inner scale factor and anisotropy factor.Compared to a Hankel–Bessel beam with diffraction-free characteristics and unfocused LG beam,the focused LG beam shows superior anti-turbulence interference properties,which provide a theoretical reference for research and development of underwater optical communication links using focused LG beams.展开更多
The discovery of high-temperature superconductivity near 80K in bilayer nickelate La_(3)Ni_(2)O_(7)under high pressures has renewed the exploration of superconducting nickelate in bulk materials.The extension of super...The discovery of high-temperature superconductivity near 80K in bilayer nickelate La_(3)Ni_(2)O_(7)under high pressures has renewed the exploration of superconducting nickelate in bulk materials.The extension of superconductivity in other nickelates in a broader family is also essential.Here,we report the experimental observation of superconducting signature in trilayer nickelate La_(4)Ni_(3)O_(10)under high pressures.By using a modified solgel method and post-annealing treatment under high oxygen pressure,we successfully obtained polycrystalline La_(4)Ni_(3)O_(10)samples with different transport behaviors at ambient pressure.Then we performed high-pressure electrical resistance measurements on these samples in a diamond-anvil-cell apparatus.Surprisingly,the signature of possible superconducting transition with a maximum transition temperature(T_(c))of about 20K under high pressures is observed,as evidenced by a clear drop of resistance and the suppression of resistance drops under magnetic fields.Although the resistance drop is sample-dependent and relatively small,it appears in all of our measured samples.We argue that the observed superconducting signal is most likely to originate from the main phase of La_(4)Ni_(3)O_(10).Our findings will motivate the exploration of superconductivity in a broader family of nickelates and shed light on the understanding of the underlying mechanisms of high-T_(c) superconductivity in nickelates.展开更多
Dzyaloshinskii–Moriya interaction(DMI) is under extensive investigation considering its crucial status in chiral magnetic orders, such as Néel-type domain wall(DW) and skyrmions. It has been reported that the in...Dzyaloshinskii–Moriya interaction(DMI) is under extensive investigation considering its crucial status in chiral magnetic orders, such as Néel-type domain wall(DW) and skyrmions. It has been reported that the interfacial DMI originating from Rashba spin–orbit coupling(SOC) can be linearly tuned with strong external electric fields. In this work, we experimentally demonstrate that the strength of DMI exhibits rapid fluctuations, ranging from 10% to 30% of its original value, as a function of applied electric fields in Pt/Co/MgO heterostructures within the small field regime(< 10-2V/nm). Brillouin light scattering(BLS) experiments have been performed to measure DMI, and first-principles calculations show agreement with this observation, which can be explained by the variation in orbital hybridization at the Co/MgO interface in response to the weak electric fields. Our results on voltage control of DMI(VCDMI) suggest that research related to the voltage control of magnetic anisotropy for spin–orbit torque or the motion control of skyrmions might also have to consider the role of the external electric field on DMI as small voltages are generally used for the magnetoresistance detection.展开更多
Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field,casting strong potentials for the device applications.In thi...Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field,casting strong potentials for the device applications.In this work,we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic simulations.We find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic coupling.In addition,we also demonstrate controllable manipulation of individual skyrmion,which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.展开更多
A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency co...A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency conversion efficiency (infrared-to-ultraviolet) is 14.3%. The power stability of the ultraviolet laser is better than 1% in 30min.展开更多
We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coatings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimen...We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coatings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimental conditions.The abrasive wear behavior and interface diffusion behavior of the composite coatings were evaluated by dry/wet rubber wheel abrasive wear tests and heat treatment,respectively.Experimental results indicate that the composite coatings exhibit features of adhesive wear.Besides,the Vickers microhardness of NiAl and Ni3Al intermetallic compounds is relatively larger than that of the substrate,which is beneficial for enhancing the wear resistance.With the increase of annealing temperature and time,the interface diffusion area between the Ni-Al coating and the substrate gradually expands with the formation of NiAl3 and Ni2Al3 phases,and is controlled by diffusion of aluminum atoms.The grain growth exponent n of diffusion kinetics of the Ni-Al coating,calculated via a high-temperature diffusion model at 400,480,and 550°C,is between 0.28 and 0.38.This satisfies the cubic law,which is consistent with the general theoretical relationship of high-temperature diffusion.展开更多
Motivated by the recent measurements of the spatial distribution of single particle excitation states in a hole-doped Mott insulator,we study the effects of impurity on the in-gap states,induced by the doped holes,in ...Motivated by the recent measurements of the spatial distribution of single particle excitation states in a hole-doped Mott insulator,we study the effects of impurity on the in-gap states,induced by the doped holes,in the Hubbard model on the square lattice by the cluster perturbation theory.We find that a repulsive impurity potential can move the in-gap state from the lower Hubbard band towards the upper Hubbard band,providing a good account for the experimental observation.The distribution of the spectral function in the momentum space can be used to discriminate the in-gap state induced by doped holes and that by the impurity.The spatial characters of the in-gap states in the presence of two impurities are also discussed and compared to the experiment.展开更多
Topological superconductors(TSCs)have been widely investigated in recent years due to their novel physics and ability to host Majorana fermions(MFs)which are key to topological quantum computation.Despite the great in...Topological superconductors(TSCs)have been widely investigated in recent years due to their novel physics and ability to host Majorana fermions(MFs)which are key to topological quantum computation.Despite the great interest,only a few compounds have been proposed as candidates of intrinsic TSCs,such as iron-based superconductor FeSe_(0.55)Te_(0.45) and 2M-WS_(2).Among them,quasi-one-dimensional superconductor TaSe_(3) possesses fascinating properties such as its simple stoichiometry,layered nature and chemical stability.Here,using scanning tunneling microscope/spectroscopy(STM/STS),we systematically investigate the topography and electronic structure of TaSe_(3).Our STM/STS measurement reveals large atomically flat,defect-free surfaces suitable for the search of MF;electronic density of states consistent with our angle-resolved photoemission result and band-structure calculations,and a uniform superconducting gap with a typical size of∼0.25 meV.Remarkably,additional edge states are observed in the vicinity of the terrace edge,suggesting they may have a topological origin.Our result proves the coexistence of superconductivity and topological electronic structure in TaSe_(3),making it an intriguing platform to investigate topological superconductivity.展开更多
This paper studies the normal state properties of itinerant electrons in a toy model,which is constructed according to the model for coexisting ferromagnetism and superconductivity proposed by Suhl [Suhl H 2001 Phys.R...This paper studies the normal state properties of itinerant electrons in a toy model,which is constructed according to the model for coexisting ferromagnetism and superconductivity proposed by Suhl [Suhl H 2001 Phys.Rev.Lett.87 167007].In this theory with ferromagnetic ordering based on localized spins,the exchange interaction J between conduction electrons and localized spin is taken as the pairing glue for s-wave superconductivity.It shows that this J term will first renormalize the normal state single conduction electron structures substantially.It finds dramatically enhanced or suppressed magnetization of itinerant electrons for positive or negative J.Singlet Cooper pairing can be ruled out due to strong spin polarisation in the J > 0 case while a narrow window for s-wave superconductivity is opened around some ferromagnetic J.展开更多
Piezocatalysis has attracted unprecedented research interest as a newly emerging catalysis technology.However,the inherent insulating property of ferroelectric materials ultimately leads to the poor vibration-electric...Piezocatalysis has attracted unprecedented research interest as a newly emerging catalysis technology.However,the inherent insulating property of ferroelectric materials ultimately leads to the poor vibration-electricity conversion ability.Herein,this work reports the(K_(0.52)Na_(0.48))NbO_(3) ferroelectric ceramics(KNNFCx),for which the FeCo modification strategy is proposed.The substitution of the moderate amount of FeCo(x=0.015)at Nb site not only optimizes ferroelectricity but also produces beneficial defects,notably increasing Rhodamine B water purification efficiency to 95%.The pinning effect of monovalent oxygen vacancies on ferroelectric domains is responsible for the excellent ferroelectric polarization of KNNFC0.015 through the generation of an internal field to promote charge carriers separation and reduce nonradiative recombination.Importantly,the accompanying electron carriers can easily move to the material surface and participate in redox reactions because they have low activation energy.Therefore,ferroelectric polarization and defects play synergetic roles in enhancing piezocatalytic performance.展开更多
The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-10Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition. ...The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-10Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition. It was found that this level ofthe master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness ofthe Al-10Mg alloy. Microchemical analysis revealed that TiC particles existed in the grain center. The relationship between the holdingtime and grain size was also studied. It shows that the grain refining efficiency is faded observably with the holding time. This is ex-plained in terms of the instability of TiC particles.展开更多
基金supported by National Natural Science Foundation of China(Nos.12175159 and 11875199)the 1000 Youth Talents Plan,startup funds from Soochow Universitythe Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘Langevin dynamical simulations are performed to determine the bulk modulus in twodimensional(2D) dusty plasmas from uniform periodic radial compressions. The bulk modulus is calculated directly from its physical definition of the ratio of the internal pressure/stress to the volume strain. Under various conditions, the bulk moduli obtained agree with the previous theoretical derivations from completely different approaches. It is found that the bulk moduli of2D Yukawa solids and liquids are almost independent of the system temperature and the external compressional frequency.
基金Project supported by National Key Research and Development Program of China (Grant No. 2019YFA0705000)the National Natural Science Foundation of China (Grant No. 11974178)。
文摘Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.
基金the support of the National Natural Science Foundation of China (Grant No.62204030)supported in part by the National Natural Science Foundation of China (Grant Nos.62122036,62034004,61921005,61974176,and 12074176)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB44000000)。
文摘InSe has emerged as a promising candidate for next-generation electronics due to its predicted ultrahigh electrical performance.However,the efficacy of the InSe transistor in meeting application requirements is hindered due to its sensitivity to interfaces.In this study,we have achieved notable enhancement in the electrical performance of InSe transistors through interface engineering.We engineered an InSe/h-BN heterostructure,effectively suppressing dielectric layer-induced scattering.Additionally,we successfully established excellent metal-semiconductor contacts using graphene ribbons as a buffer layer.Through a methodical approach to interface engineering,our graphene/InSe/h-BN transistor demonstrates impressive on-state current,field-effect mobility,and on/off ratio at room temperature,reaching values as high as 1.1 mA/μm,904 cm^(2)·V^(-1)·s^(-1),and>10~6,respectively.Theoretical computations corroborate that the graphene/InSe heterostructure shows significant interlayer charge transfer and weak interlayer interaction,contributing to the enhanced performance of InSe transistors.This research offers a comprehensive strategy to elevate the electrical performance of InSe transistors,paving the way for their utilization in future electronic applications.
基金Project supported by the Open Project of the Key Laboratory of Xinjiang Uygur Autonomous Region,China(Grant No.2021D04015)the Yili Kazakh Autonomous Prefecture Science and Technology Program Project,China(Grant No.YZ2022B021).
文摘Fractional molecular field theory(FMFT)is a phenomenological theory that describes phase transitions in crystals with randomly distributed components,such as the relaxor-ferroelectrics and spin glasses.In order to verify the feasibility of this theory,this paper fits it to the Monte Carlo simulations of specific heat and susceptibility versus temperature of two-dimensional(2D)random-site Ising model(2D-RSIM).The results indicate that the FMFT deviates from the 2D-RSIM significantly.The main reason for the deviation is that the 2D-RSIM is a typical system of component random distribution,where the real order parameter is spatially heterogeneous and has no symmetry of space translation,but the basic assumption of FMFT means that the parameter is spatially uniform and has symmetry of space translation.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375140 and 61871234)the Open Research Fund of National Laboratory of Solid State Microstructures(Grant No.M36055).
文摘Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM modes.In this paper,we propose a novel OAM hologram generation method based on a densely connected U-net(DCU),where the densely connected convolution blocks(DCB)replace the convolution blocks of the U-net.Importantly,the reconstruction process of the OAM hologram is integrated into DCU as its output layer,so as to eliminate the requirement to prepare training data for the OAM hologram,which is required by conventional neural networks through an iterative algorithm.The experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU,and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method,the Gerchberg-Saxton based generation method and the U-net method.In addition,a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram.
基金Project supported by the National Key Research and Development Program of China (Grant No.2021YFA1400400)the National Natural Science Foundation of China (Grant Nos.92165205,12074175,and 12374137)。
文摘By utilizing the fluctuation exchange approximation method,we perform a study on the superconducting pairing symmetry in a t_(2g) three-orbital model on the square lattice.Although the tight-binding parameters of the model are based on Sr_(2)RuO_(4),we have systematically studied the evolution of superconducting pairing symmetry with the carrier density and interactions,making our findings relevant to a broader range of material systems.Under a moderate Hund’s coupling,we find that spin fluctuations dominate the superconducting pairing,leading to a prevalent spin-singlet pairing with a d_(x^(2)-y^(2))-wave symmetry for the carrier density within the range of n=1.5-4 per site.By reducing the Hund’s coupling,the charge fluctuations are enhanced and play a crucial role in determining the pairing symmetry,leading to a transition of the pairing symmetry from the spin-singlet d_(x^(2)-y^(2))-wave to the spin-triplet p-wave.Furthermore,we find that the superconducting pairings are orbital dependent.As the carrier density changes from n=4 to n=1.5,the active orbitals for superconducting pairing shift from the quasi-two-dimensional orbital dxy to the quasi-one-dimensional orbitals d_(xz) and d_(yz).
基金This work was supported by the Science and Technology Innovation Training Program of Nanjing University of Posts and Telecommunications(Grant No.CXXZD2023080)the National Natural Science Foundation of China(Grant Nos.61871234 and 62001249)+1 种基金the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY222133)the Open Research Fund of National Laboratory of Solid State Microstructures(Grant No.M36055).
文摘We analyze the properties of a focused Laguerre–Gaussian(LG)beam propagating through anisotropic ocean turbulence based on the Huygens–Fresnel principle.Under the Rytov approximation theory,we derive the analytical formula of the channel capacity of the focused LG beam in the anisotropic ocean turbulence,and analyze the relationship between the capacity and the light source parameters as well as the turbulent ocean parameters.It is found that the focusing mirror can greatly enhance the channel capacity of the system at the geometric focal plane in oceanic turbulence.The results also demonstrate that the communication link can obtain high channel capacity by adopting longer beam wavelength,greater initial beam waist radius,and larger number of transmission channels.Further,the capacity of the system increases with the decrease of the mean squared temperature dissipation rate,temperature-salinity contribution ratio and turbulence outer scale factor,and with the increase of the kinetic energy dissipation rate per unit mass of fluid,turbulence inner scale factor and anisotropy factor.Compared to a Hankel–Bessel beam with diffraction-free characteristics and unfocused LG beam,the focused LG beam shows superior anti-turbulence interference properties,which provide a theoretical reference for research and development of underwater optical communication links using focused LG beams.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1403201)the National Natural Science Foundation of China(Grant Nos.12204231,12061131001,52072170,and 11927809)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB25000000).
文摘The discovery of high-temperature superconductivity near 80K in bilayer nickelate La_(3)Ni_(2)O_(7)under high pressures has renewed the exploration of superconducting nickelate in bulk materials.The extension of superconductivity in other nickelates in a broader family is also essential.Here,we report the experimental observation of superconducting signature in trilayer nickelate La_(4)Ni_(3)O_(10)under high pressures.By using a modified solgel method and post-annealing treatment under high oxygen pressure,we successfully obtained polycrystalline La_(4)Ni_(3)O_(10)samples with different transport behaviors at ambient pressure.Then we performed high-pressure electrical resistance measurements on these samples in a diamond-anvil-cell apparatus.Surprisingly,the signature of possible superconducting transition with a maximum transition temperature(T_(c))of about 20K under high pressures is observed,as evidenced by a clear drop of resistance and the suppression of resistance drops under magnetic fields.Although the resistance drop is sample-dependent and relatively small,it appears in all of our measured samples.We argue that the observed superconducting signal is most likely to originate from the main phase of La_(4)Ni_(3)O_(10).Our findings will motivate the exploration of superconductivity in a broader family of nickelates and shed light on the understanding of the underlying mechanisms of high-T_(c) superconductivity in nickelates.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61627813,62204018,and 61571023)the Beijing Municipal Science and Technology Project(Grant No.Z201100004220002)+2 种基金the National Key Technology Program of China(Grant No.2017ZX01032101)the Program of Introducing Talents of Discipline to Universities in China(Grant No.B16001)the VR Innovation Platform from Qingdao Science and Technology Commission.
文摘Dzyaloshinskii–Moriya interaction(DMI) is under extensive investigation considering its crucial status in chiral magnetic orders, such as Néel-type domain wall(DW) and skyrmions. It has been reported that the interfacial DMI originating from Rashba spin–orbit coupling(SOC) can be linearly tuned with strong external electric fields. In this work, we experimentally demonstrate that the strength of DMI exhibits rapid fluctuations, ranging from 10% to 30% of its original value, as a function of applied electric fields in Pt/Co/MgO heterostructures within the small field regime(< 10-2V/nm). Brillouin light scattering(BLS) experiments have been performed to measure DMI, and first-principles calculations show agreement with this observation, which can be explained by the variation in orbital hybridization at the Co/MgO interface in response to the weak electric fields. Our results on voltage control of DMI(VCDMI) suggest that research related to the voltage control of magnetic anisotropy for spin–orbit torque or the motion control of skyrmions might also have to consider the role of the external electric field on DMI as small voltages are generally used for the magnetoresistance detection.
基金Project supported by the National Key R&D Program of China(Grant Nos.2021YFB3502400 and 2022YFA1403601)the National Natural Science Foundation of China(Grant Nos.12274204,12274203,51831005,52172270,11974165,92165103,51971110,12004329,and 12241402).
文摘Recent theory and experiments show that artificial magnetic skyrmions can be stabilized at room temperature without the need for the external magnetic field,casting strong potentials for the device applications.In this work,we study the electric field manipulation of artificial magnetic skyrmions imprinted by Co disks on CoPt multilayers utilizing the micromagnetic simulations.We find that the reversible annihilation and creation of skyrmions can be realized with the electric field via the strain mediated magnetoelastic coupling.In addition,we also demonstrate controllable manipulation of individual skyrmion,which opens a new platform for constructing magnetic field-free and low-energy dissipation skyrmion based media.
基金Supported by the National Natural Science Foundation of China under Grant No.60078011in part by an Open Project of the National Laboratory of Solid State Microstructure,Nanjing University.
文摘A maximum of 310mW average output power at 355nm has been obtained by extracavity frequency tripling with a BBO crystal in a Q-switched Nd:YV04 laser with 11.2 W of laser diode pump power. The single pass frequency conversion efficiency (infrared-to-ultraviolet) is 14.3%. The power stability of the ultraviolet laser is better than 1% in 30min.
基金financially supported by the International Cooperation Project of the Ministry of Science and Technology of China(ICPMSTPRC,No.2008DFR50070)
文摘We have systematically studied the microstructure and mechanical properties of Ni-5wt%Al and Ni-20wt%Al composite coatings fabricated on 6061-T6 aluminum alloy sheet by twin-wire arc spraying under different experimental conditions.The abrasive wear behavior and interface diffusion behavior of the composite coatings were evaluated by dry/wet rubber wheel abrasive wear tests and heat treatment,respectively.Experimental results indicate that the composite coatings exhibit features of adhesive wear.Besides,the Vickers microhardness of NiAl and Ni3Al intermetallic compounds is relatively larger than that of the substrate,which is beneficial for enhancing the wear resistance.With the increase of annealing temperature and time,the interface diffusion area between the Ni-Al coating and the substrate gradually expands with the formation of NiAl3 and Ni2Al3 phases,and is controlled by diffusion of aluminum atoms.The grain growth exponent n of diffusion kinetics of the Ni-Al coating,calculated via a high-temperature diffusion model at 400,480,and 550°C,is between 0.28 and 0.38.This satisfies the cubic law,which is consistent with the general theoretical relationship of high-temperature diffusion.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0302901 and 2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.11888101,12074175,and 92165205)。
文摘Motivated by the recent measurements of the spatial distribution of single particle excitation states in a hole-doped Mott insulator,we study the effects of impurity on the in-gap states,induced by the doped holes,in the Hubbard model on the square lattice by the cluster perturbation theory.We find that a repulsive impurity potential can move the in-gap state from the lower Hubbard band towards the upper Hubbard band,providing a good account for the experimental observation.The distribution of the spectral function in the momentum space can be used to discriminate the in-gap state induced by doped holes and that by the impurity.The spatial characters of the in-gap states in the presence of two impurities are also discussed and compared to the experiment.
基金Supported by the National Key R&D Program of China(Grant No.2017YFA0305400)the Shanghai Technology Innovation Action Plan 2020-Integrated Circuit Technology Support Program(Grant No.20DZ1100605)+2 种基金the National Natural Science Foundation of China(Grant Nos.52072168,21733001,51861145201,U1932217,and 11974246)the National Key Basic Research Program of China(Grant No.2018YFA0306200)the Science and Technology Commission of Shanghai Municipality(Grant No.19JC1413900).
文摘Topological superconductors(TSCs)have been widely investigated in recent years due to their novel physics and ability to host Majorana fermions(MFs)which are key to topological quantum computation.Despite the great interest,only a few compounds have been proposed as candidates of intrinsic TSCs,such as iron-based superconductor FeSe_(0.55)Te_(0.45) and 2M-WS_(2).Among them,quasi-one-dimensional superconductor TaSe_(3) possesses fascinating properties such as its simple stoichiometry,layered nature and chemical stability.Here,using scanning tunneling microscope/spectroscopy(STM/STS),we systematically investigate the topography and electronic structure of TaSe_(3).Our STM/STS measurement reveals large atomically flat,defect-free surfaces suitable for the search of MF;electronic density of states consistent with our angle-resolved photoemission result and band-structure calculations,and a uniform superconducting gap with a typical size of∼0.25 meV.Remarkably,additional edge states are observed in the vicinity of the terrace edge,suggesting they may have a topological origin.Our result proves the coexistence of superconductivity and topological electronic structure in TaSe_(3),making it an intriguing platform to investigate topological superconductivity.
基金supported by the National Natural Science Foundation of China (Grant No. 10574063)
文摘This paper studies the normal state properties of itinerant electrons in a toy model,which is constructed according to the model for coexisting ferromagnetism and superconductivity proposed by Suhl [Suhl H 2001 Phys.Rev.Lett.87 167007].In this theory with ferromagnetic ordering based on localized spins,the exchange interaction J between conduction electrons and localized spin is taken as the pairing glue for s-wave superconductivity.It shows that this J term will first renormalize the normal state single conduction electron structures substantially.It finds dramatically enhanced or suppressed magnetization of itinerant electrons for positive or negative J.Singlet Cooper pairing can be ruled out due to strong spin polarisation in the J > 0 case while a narrow window for s-wave superconductivity is opened around some ferromagnetic J.
基金Supported by the National Natural Science Foundation of China under Grant No 90503012, and the National Basic Research Programme of China under Grant Nos 2004CB619004 and 2006CB921803.
基金supported by the National Natural Science Foundation of China (Nos.52172116 and 62171214)the Natural Science Basic Research Program of Shaanxi (Nos.2021JQ-655,2020JQ-828,2021JQ-188,2021JM-442,and 2020JQ-822)+2 种基金the Shaanxi Provincial Association of Science and Technology Youth Talents Lifting Plan (No.20180418)the Scientific Research Foundation for Ph.D.of Xi’an Polytechnic University (No.BS201877)the Special Scientific Research Project in Shaanxi Province Department of Education (No.21JK0653).
文摘Piezocatalysis has attracted unprecedented research interest as a newly emerging catalysis technology.However,the inherent insulating property of ferroelectric materials ultimately leads to the poor vibration-electricity conversion ability.Herein,this work reports the(K_(0.52)Na_(0.48))NbO_(3) ferroelectric ceramics(KNNFCx),for which the FeCo modification strategy is proposed.The substitution of the moderate amount of FeCo(x=0.015)at Nb site not only optimizes ferroelectricity but also produces beneficial defects,notably increasing Rhodamine B water purification efficiency to 95%.The pinning effect of monovalent oxygen vacancies on ferroelectric domains is responsible for the excellent ferroelectric polarization of KNNFC0.015 through the generation of an internal field to promote charge carriers separation and reduce nonradiative recombination.Importantly,the accompanying electron carriers can easily move to the material surface and participate in redox reactions because they have low activation energy.Therefore,ferroelectric polarization and defects play synergetic roles in enhancing piezocatalytic performance.
基金Supported by the National Nature Science Foundation of China under Grant No 10574063, and the Specialized Research Fund for the Doctoral Programme of Higher Education （SRFDP） under Grant No 20030284008.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10274069, 60471052, and 10347003, Natural Science Foundation of Zhejiang Province of China under Grant No. M603193, and the National Laboratory of Solid State Microstructures in Nanjing University under Grant No. M031802
基金This work was financially supported by the National Natural Science Foundation of China (No. 50231040).
文摘The microstructure and microhardness of a cast Al-10wt%Mg (henceforth Al-10Mg) alloy with 0.2wt% addition of Al-5Ti-0.25C master alloy were compared with those of a refiner-free alloy of similar chemical composition. It was found that this level ofthe master alloy addition not only caused an effective grain refinement, but also caused a significant increase in the microhardness ofthe Al-10Mg alloy. Microchemical analysis revealed that TiC particles existed in the grain center. The relationship between the holdingtime and grain size was also studied. It shows that the grain refining efficiency is faded observably with the holding time. This is ex-plained in terms of the instability of TiC particles.
