Two-dimensional(2D)materials have demonstrated promising prospects owing to their distinctive electronic properties and exceptional mechanical properties.Among them,2D superconductors with T_(c) above the boiling poin...Two-dimensional(2D)materials have demonstrated promising prospects owing to their distinctive electronic properties and exceptional mechanical properties.Among them,2D superconductors with T_(c) above the boiling point of liquid nitrogen(77 K)will exhibit tremendous applicable value in the future.Here,we design two 2D superconductors Na(BC)_(2) and K(BC)_(2) with MgB2-like structures,which are theoretically predicted to host T_(c) as high as 99 and 102 K,respectively.The origin of such high T_(c) is ascribed to the presence of both𝜎-bonding bands and van Hove singularity at the Fermi level.Furthermore,T_(c) of Na(BC)_(2) is boosted up to 153K with a biaxial strain of 5%,which sets a new record among 2D superconductors.The predictions of Na(BC)_(2) and K(BC)_(2) open the door to explore 2D high-temperature superconductors and provide a potential future for developing new applications in 2D materials.展开更多
Recently,room-temperature superconductivity has been reported in a nitrogen-doped lutetium hydride at near-ambient pressure[Dasenbrock-Gammon et al.,Nature 615,244(2023)].The superconducting properties might arise fro...Recently,room-temperature superconductivity has been reported in a nitrogen-doped lutetium hydride at near-ambient pressure[Dasenbrock-Gammon et al.,Nature 615,244(2023)].The superconducting properties might arise from Fm3m-LuH_(3)−δNε.Here,we systematically study the phase diagram of Lu–N–H at 1 GPa using first-principles calculations,and we do not find any thermodynamically stable ternary compounds.In addition,we calculate the dynamic stability and superconducting properties of N-doped Fm3m-LuH_(3) using the virtual crystal approximation(VCA)and the supercell method.The R3m-Lu_(2)H_(5)N predicted using the supercell method could be dynamically stable at 50 GPa,with a T_(c) of 27 K.According to the VCA method,the highest T_(c) is 22 K,obtained with 1%N-doping at 30 GPa.Moreover,the doping of nitrogen atoms into Fm3m-LuH_(3) slightly enhances T_(c),but raises the dynamically stable pressure.Our theoretical results show that the T_(c) values of N-doped LuH_(3) estimated using the Allen–Dynes-modified McMillan equation are much lower than room temperature.展开更多
Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity.Here,we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity o...Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity.Here,we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice,and predict an unprecedented layered compound Na_(2)B_(2)H,which hosts excellent superconductivity.Strikingly,the superconducting transition temperature(Tc)of Na_(2)B_(2)H reaches 42 K at ambient pressure.The Tcvalue can be further increase to 63 K under 5%biaxial tensile strain.The excellent superconductivity originates from the strong electron-phonon coupling between theσ-bonding bands near the Fermi level and the B-B stretching optical E modes.The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer.Furthermore,the introduction of hydrogen tuned the Fermi level,and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure.Na_(2)B_(2)H represents a new family of layered high-temperature superconductors,and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds.展开更多
Superconductivity in compressed sulfur hydride(H_(3)S)at above 200 K has attracted great interest in the study of hydrogen-based superconductors.However,the pressure required to stabilize H_(3)S is 150 GPa,posing sign...Superconductivity in compressed sulfur hydride(H_(3)S)at above 200 K has attracted great interest in the study of hydrogen-based superconductors.However,the pressure required to stabilize H_(3)S is 150 GPa,posing significant challenges for experiments.Therefore,it is essential to find a strategy to reduce this pressure.In this study,by introducing halogen atoms into the H-S system,we discovered that hydrogen-based superconductors of H_(6)SX(X=Cl and Br)can be dynamically stable at mild pressures(5 GPa for H_(6)SCl and H_(6)SBr),as confirmed by first-principles calculations.Through the analysis of the bond properties,we revealed that introducing halogen elements would strengthen the H–S covalent bonds to reduce the dynamically stable pressure of H_(3)S.Our study provides a scheme to reduce the superconducting pressure of hydrogen-based superconductors.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12122405 and 12274169)the National Key Research and Development Program of China(Grant Nos.2022YFA1402304 and 2023YFA1406200)the Fundamental Research Funds for the Central Universities。
文摘Two-dimensional(2D)materials have demonstrated promising prospects owing to their distinctive electronic properties and exceptional mechanical properties.Among them,2D superconductors with T_(c) above the boiling point of liquid nitrogen(77 K)will exhibit tremendous applicable value in the future.Here,we design two 2D superconductors Na(BC)_(2) and K(BC)_(2) with MgB2-like structures,which are theoretically predicted to host T_(c) as high as 99 and 102 K,respectively.The origin of such high T_(c) is ascribed to the presence of both𝜎-bonding bands and van Hove singularity at the Fermi level.Furthermore,T_(c) of Na(BC)_(2) is boosted up to 153K with a biaxial strain of 5%,which sets a new record among 2D superconductors.The predictions of Na(BC)_(2) and K(BC)_(2) open the door to explore 2D high-temperature superconductors and provide a potential future for developing new applications in 2D materials.
基金This work was supported by the National Key R&D Program of China(Grant Nos.2018YFA0305900 and 2022YFA1402304)the National Natural Science Foundation of China(Grant Nos.12122405,52072188,and 12274169)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT_15R23)a Jilin Provincial Science and Technology Development Project(Grant No.20210509038RQ).Some of the calculations were performed at the High Performance Computing Center of Jilin University and on TianHe-1(A)at the National Supercomputer Center in Tianjin.
文摘Recently,room-temperature superconductivity has been reported in a nitrogen-doped lutetium hydride at near-ambient pressure[Dasenbrock-Gammon et al.,Nature 615,244(2023)].The superconducting properties might arise from Fm3m-LuH_(3)−δNε.Here,we systematically study the phase diagram of Lu–N–H at 1 GPa using first-principles calculations,and we do not find any thermodynamically stable ternary compounds.In addition,we calculate the dynamic stability and superconducting properties of N-doped Fm3m-LuH_(3) using the virtual crystal approximation(VCA)and the supercell method.The R3m-Lu_(2)H_(5)N predicted using the supercell method could be dynamically stable at 50 GPa,with a T_(c) of 27 K.According to the VCA method,the highest T_(c) is 22 K,obtained with 1%N-doping at 30 GPa.Moreover,the doping of nitrogen atoms into Fm3m-LuH_(3) slightly enhances T_(c),but raises the dynamically stable pressure.Our theoretical results show that the T_(c) values of N-doped LuH_(3) estimated using the Allen–Dynes-modified McMillan equation are much lower than room temperature.
基金supported by the National Natural Science Foundation of China(Grant Nos.52072188,12122405,and 12274169)the National Key Research and Development Program of China(Grant No.2022YFA1402304)+5 种基金the Program for Science and Technology Innovation Team in Zhejiang(Grant No.2021R01004)the Fundamental Research Funds for the Central Universitiesthe support of the National Science Foundation(NSF)(Grant Nos.Division of Materials Research(DMR)-1848141 and Office of Advanced Cyberinfrastructure(OAC)-2117956)the Camille and Henry Dreyfus Foundationthe California State University Research,ScholarshipCreative Activity(RSCA)award。
文摘Hydrogenated metal borides have attracted much attention due to their potential high-temperature superconductivity.Here,we propose a new strategy for hydrogen intercalation tuning the stability and superconductivity of the boron honeycomb sublattice,and predict an unprecedented layered compound Na_(2)B_(2)H,which hosts excellent superconductivity.Strikingly,the superconducting transition temperature(Tc)of Na_(2)B_(2)H reaches 42 K at ambient pressure.The Tcvalue can be further increase to 63 K under 5%biaxial tensile strain.The excellent superconductivity originates from the strong electron-phonon coupling between theσ-bonding bands near the Fermi level and the B-B stretching optical E modes.The interstitial electron localization and crystal orbitals of the H-intercalated Na ion layer well match the boron honeycomb lattice and act as a chemical template to stabilize the B layer.Furthermore,the introduction of hydrogen tuned the Fermi level,and the coupling vibration of Na and H ions effectively enhanced the dynamic stability of the structure.Na_(2)B_(2)H represents a new family of layered high-temperature superconductors,and the strategy of stabilizing the honeycomb boron sublattice via chemical template hosts great potential for application to more layered compounds.
基金supported by the National Natural Science Foundation of China(Grant Nos.12122405,52072188,and 12274169)the National Key R&D Program of China(Grant No.2022YFA1402304)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT_15R23)the Jilin Provincial Science and Technology Development Project(Grant No.20210509038RQ)。
文摘Superconductivity in compressed sulfur hydride(H_(3)S)at above 200 K has attracted great interest in the study of hydrogen-based superconductors.However,the pressure required to stabilize H_(3)S is 150 GPa,posing significant challenges for experiments.Therefore,it is essential to find a strategy to reduce this pressure.In this study,by introducing halogen atoms into the H-S system,we discovered that hydrogen-based superconductors of H_(6)SX(X=Cl and Br)can be dynamically stable at mild pressures(5 GPa for H_(6)SCl and H_(6)SBr),as confirmed by first-principles calculations.Through the analysis of the bond properties,we revealed that introducing halogen elements would strengthen the H–S covalent bonds to reduce the dynamically stable pressure of H_(3)S.Our study provides a scheme to reduce the superconducting pressure of hydrogen-based superconductors.
