The density functional calculation is performed for centrosymmetric（La–Pm） GaO3 rare earth gallates, using a full potential linear augmented plane wave method with the LSDA and LSDA＋U exchange correlation to treat...The density functional calculation is performed for centrosymmetric（La–Pm） GaO3 rare earth gallates, using a full potential linear augmented plane wave method with the LSDA and LSDA＋U exchange correlation to treat highly correlated electrons due to the very localized 4f orbitals of rare earth elements, and explore the influence of U = 0.478 Ry on the magnetic phase stability and the densities of states. LSDA＋U calculation shows that the ferromagnetic（FM） state of RGaO3 is energetically more favorable than the anti-ferromagnetic（AFM） one, except for LaGaO3 where the NM state is the lowest in energy. The energy band gaps of RGaO3 are found to be in the range of 3.8–4.0 eV, indicating the semiconductor character with a large gap.展开更多
Raman scattering is a versatile and powerful technique and has been widely used in modern scientific research and vast industrial applications. It is one of the fundamental experimental techniques in condensed matter ...Raman scattering is a versatile and powerful technique and has been widely used in modern scientific research and vast industrial applications. It is one of the fundamental experimental techniques in condensed matter physics, since it can sensitively probe the basic elementary excitations in solids like electron, phonon, magnon, etc. The application of extreme conditions （low temperature, high magnetic field, high pressure, etc.） to Raman scattering, will push its capability up to an unprecedented level, because this enables us to look into new quantum phases driven by extreme conditions, trace the evolution of the excitations and their coupling, and hence uncover the underlying physics. This review contains two topics. In the first part, we will introduce the Raman facility under extreme conditions, belonging to the optical spectroscopy station of Synergetic Extreme Condition User Facilities （SECUF）, with emphasis on the system design and the capability the facility can provide. Then in the second part we will focus on the applications of Raman scattering under extreme conditions to a variety of condensed matter systems such as superconductors, correlated electron systems, charge density waves （CDW） materials, etc. Finally, as a rapidly developing technique, time-resolved Raman scattering will be highlighted here.展开更多
The effect ofthe edge state on the persistent current in quasi-1D mesoscopic rings with a screened interactionwhich exists only between nearest-neighboring particles is studied with the Hartree-Fock approximation. The...The effect ofthe edge state on the persistent current in quasi-1D mesoscopic rings with a screened interactionwhich exists only between nearest-neighboring particles is studied with the Hartree-Fock approximation. The theoreticalvalue of the current magnitude is greatly enhanced by both the edge state and the Coulomb interaction, and pinningthe electrons into a lattice is good for the enhancement if screening happens. In high dimensional systems the screeningeffect can make the interacting range show anisotropy, and create a tendency of gathering for particles with a repulsivepotential.展开更多
Transition metal oxides with 4d or 5d metals are of great interest due to the competing interactions, of the Coulomb repulsion and the itineracy of the d-electrons, opening a possibility of building new quantum ground...Transition metal oxides with 4d or 5d metals are of great interest due to the competing interactions, of the Coulomb repulsion and the itineracy of the d-electrons, opening a possibility of building new quantum ground states. Particularly the 5d metal oxides containing Iridium have received significant attention within the last years, due to their unexpected physical properties, caused by a strong spin orbit coupling observed in It（IV）. A prominent example is the Mott-insulator Sr2IrO4. Another member of this family, the honeycomb lattice compound Na2IrO3, also being a Mott-insulator having, most probably, a Kitaev spin liquid ground state. By deintercalating sodium from Na2IrO3, the authors were able to synthesize a new honeycomb lattice compound with more than 50% reduced sodium content. The reduction of the sodium content in this layered compound leads to a change of the oxidation state of iridium from ＋ IV to ＋ V/＋ VI and a symmetry change from C2/c to P-3. This goes along with significant changes of the physical properties. Besides the vanishing magnetic ordering at 15 K, also the transport properties changes and instead insulating semiconducting properties are observed.展开更多
In this paper, we explored the structural, elastic and mechanical properties of the strongly correlated electron systems, intermetallic Ln-Au（Ln = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu） in cubic structure,using...In this paper, we explored the structural, elastic and mechanical properties of the strongly correlated electron systems, intermetallic Ln-Au（Ln = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu） in cubic structure,using PF-LAPW method within the density functional theory. Structural properties of these intermetallics were investigated by treating the exchange-correlation potential with the GGA-PBE, GGA-PBEsol and GGA ＋ U. The effectiveness of the U for the structural properties as compared to other methods confirms the strong correlated nature of these compounds and the calculated lattice constants endorse the divalency of Yb. The results demonstrate the stable cubic CsCl structure of these compounds. Bulk modulus, Young＇s modulus, shear modulus, B/G ratio, Cauchy pressure, Poisson＇s ratio, anisotropic ratio,Kleinman parameters and Lame＇s coefficients were studied using the PBEsol to evaluate their importance in various types of engineering applications. The most prominent features of these compounds are their ductility, very high melting points, resistance to corrosion, and anisotropic nature.展开更多
We reveal and explain the scaling behavior of the thermopower S/T exhibited by the archetypal heavy-fermion （HF） metal YbRh2Si2 under the application of magnetic field B at temperature T. We show that the same scali...We reveal and explain the scaling behavior of the thermopower S/T exhibited by the archetypal heavy-fermion （HF） metal YbRh2Si2 under the application of magnetic field B at temperature T. We show that the same scaling is demonstrated by different HF compounds such as/3-YbA1B4 and the strongly correlated layered cobalt oxide [BiBa0.66K0.3602]CoO2. Using YbRh2Si2 as an example, we demonstrate that the scaling behavior of SIT is violated at the antiferromagnetic phase transition, while both the residual resistivity Po and the density of states, N, experience jumps at the phase transition, causing the thermopower to make two jumps and change its sign. Our elucidation is based on flattening of the single-particle spectrum that profoundly affects Po and N. To depict the main features of the SIT behavior, we construct a T-B schematic phase diagram of YbRh2Si2. Our calculated SIT for the HF compounds are in good agreement with experimental facts and support our observations.展开更多
文摘The density functional calculation is performed for centrosymmetric（La–Pm） GaO3 rare earth gallates, using a full potential linear augmented plane wave method with the LSDA and LSDA＋U exchange correlation to treat highly correlated electrons due to the very localized 4f orbitals of rare earth elements, and explore the influence of U = 0.478 Ry on the magnetic phase stability and the densities of states. LSDA＋U calculation shows that the ferromagnetic（FM） state of RGaO3 is energetically more favorable than the anti-ferromagnetic（AFM） one, except for LaGaO3 where the NM state is the lowest in energy. The energy band gaps of RGaO3 are found to be in the range of 3.8–4.0 eV, indicating the semiconductor character with a large gap.
基金Project supported by the Ministry of Science and Technology of China(Grant Nos.2016YFA0300504 and 2017YFA0302904)the National Natural Science Foundation of China(Grant Nos.11474357,11774419,11604383,and 11704401)supported by the Scientific Equipment Development Project of Chinese Academy of Sciences(Grant No.YJKYYQ20170027)
文摘Raman scattering is a versatile and powerful technique and has been widely used in modern scientific research and vast industrial applications. It is one of the fundamental experimental techniques in condensed matter physics, since it can sensitively probe the basic elementary excitations in solids like electron, phonon, magnon, etc. The application of extreme conditions （low temperature, high magnetic field, high pressure, etc.） to Raman scattering, will push its capability up to an unprecedented level, because this enables us to look into new quantum phases driven by extreme conditions, trace the evolution of the excitations and their coupling, and hence uncover the underlying physics. This review contains two topics. In the first part, we will introduce the Raman facility under extreme conditions, belonging to the optical spectroscopy station of Synergetic Extreme Condition User Facilities （SECUF）, with emphasis on the system design and the capability the facility can provide. Then in the second part we will focus on the applications of Raman scattering under extreme conditions to a variety of condensed matter systems such as superconductors, correlated electron systems, charge density waves （CDW） materials, etc. Finally, as a rapidly developing technique, time-resolved Raman scattering will be highlighted here.
文摘The effect ofthe edge state on the persistent current in quasi-1D mesoscopic rings with a screened interactionwhich exists only between nearest-neighboring particles is studied with the Hartree-Fock approximation. The theoreticalvalue of the current magnitude is greatly enhanced by both the edge state and the Coulomb interaction, and pinningthe electrons into a lattice is good for the enhancement if screening happens. In high dimensional systems the screeningeffect can make the interacting range show anisotropy, and create a tendency of gathering for particles with a repulsivepotential.
文摘Transition metal oxides with 4d or 5d metals are of great interest due to the competing interactions, of the Coulomb repulsion and the itineracy of the d-electrons, opening a possibility of building new quantum ground states. Particularly the 5d metal oxides containing Iridium have received significant attention within the last years, due to their unexpected physical properties, caused by a strong spin orbit coupling observed in It（IV）. A prominent example is the Mott-insulator Sr2IrO4. Another member of this family, the honeycomb lattice compound Na2IrO3, also being a Mott-insulator having, most probably, a Kitaev spin liquid ground state. By deintercalating sodium from Na2IrO3, the authors were able to synthesize a new honeycomb lattice compound with more than 50% reduced sodium content. The reduction of the sodium content in this layered compound leads to a change of the oxidation state of iridium from ＋ IV to ＋ V/＋ VI and a symmetry change from C2/c to P-3. This goes along with significant changes of the physical properties. Besides the vanishing magnetic ordering at 15 K, also the transport properties changes and instead insulating semiconducting properties are observed.
基金Project supported by the Higher Education Commission of Pakistan(HEC)(20-3959/NRPU/R&D/HEC2014/119)
文摘In this paper, we explored the structural, elastic and mechanical properties of the strongly correlated electron systems, intermetallic Ln-Au（Ln = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu） in cubic structure,using PF-LAPW method within the density functional theory. Structural properties of these intermetallics were investigated by treating the exchange-correlation potential with the GGA-PBE, GGA-PBEsol and GGA ＋ U. The effectiveness of the U for the structural properties as compared to other methods confirms the strong correlated nature of these compounds and the calculated lattice constants endorse the divalency of Yb. The results demonstrate the stable cubic CsCl structure of these compounds. Bulk modulus, Young＇s modulus, shear modulus, B/G ratio, Cauchy pressure, Poisson＇s ratio, anisotropic ratio,Kleinman parameters and Lame＇s coefficients were studied using the PBEsol to evaluate their importance in various types of engineering applications. The most prominent features of these compounds are their ductility, very high melting points, resistance to corrosion, and anisotropic nature.
文摘We reveal and explain the scaling behavior of the thermopower S/T exhibited by the archetypal heavy-fermion （HF） metal YbRh2Si2 under the application of magnetic field B at temperature T. We show that the same scaling is demonstrated by different HF compounds such as/3-YbA1B4 and the strongly correlated layered cobalt oxide [BiBa0.66K0.3602]CoO2. Using YbRh2Si2 as an example, we demonstrate that the scaling behavior of SIT is violated at the antiferromagnetic phase transition, while both the residual resistivity Po and the density of states, N, experience jumps at the phase transition, causing the thermopower to make two jumps and change its sign. Our elucidation is based on flattening of the single-particle spectrum that profoundly affects Po and N. To depict the main features of the SIT behavior, we construct a T-B schematic phase diagram of YbRh2Si2. Our calculated SIT for the HF compounds are in good agreement with experimental facts and support our observations.
