Auxetic two-dimensional(2D)materials provide a promising platform for biomedicine,sensors,and many other applications at the nanoscale.In this work,utilizing a hypothesis-based data-driven approache,we identify multip...Auxetic two-dimensional(2D)materials provide a promising platform for biomedicine,sensors,and many other applications at the nanoscale.In this work,utilizing a hypothesis-based data-driven approache,we identify multiple materials with remarkable in-plane auxetic behavior in a family of buckled monolayer 2D materials.These materials are transition metal selenides and transition metal halides with the stoichiometry MX(M=V,Cr,Mn,Fe,Co,Cu,Zn,Ag,and X=Se,Cl,Br,I).First-principles calculations reveal that the desirable auxetic behavior of these 2D compounds originates from the interplay between the buckled 2D structure and the weak metal-metal interaction determined by their electronic structures.We observe that the Poisson’s ratio is sensitive to magnetic order and the amount of uniaxial stress applied.A transition from positive Poisson’s ratio(PPR)to negative Poisson’s ratio(NPR)for a subgroup of MX compounds under large uniaxial stress is predicted.The work provides a guideline for the future design of 2D auxetic materials at the nanoscale.展开更多
We propose a novel class of two-dimensional(2D)Dirac materials in the MX family(M=Be,Mg,Zn and Cd,X=Cl,Br and I),which exhibit graphene-like band structures with linearly-dispersing Dirac-cone states over large energy...We propose a novel class of two-dimensional(2D)Dirac materials in the MX family(M=Be,Mg,Zn and Cd,X=Cl,Br and I),which exhibit graphene-like band structures with linearly-dispersing Dirac-cone states over large energy scales(0.8–1.8 eV)and ultra-high Fermi velocities comparable to graphene.Spin-orbit coupling opens sizable topological band gaps so that these compounds can be effectively classified as quantum spin Hall insulators.The electronic and topological properties are found to be highly tunable and amenable to modulation via anion-layer substitution and vertical electric field.Electronic structures of several members of the family are shown to host a Van-Hove singularity(VHS)close to the energy of the Dirac node.The enhanced density-of-states associated with these VHSs could provide a mechanism for inducing topological superconductivity.The presence of sizable band gaps,ultra-high carrier mobilities,and small effective masses makes the MX family promising for electronics and spintronics applications.展开更多
基金This work was supported as part of the Center for Complex Materials from First Principles(CCM),an Energy Frontier Research Center funded by the US Department of Energy(DOE),Office of Science,Basic Energy Sciences(BES),under Award DESC0012575L.Yu was supported by the US Department of Energy(DOE)under Award DE-SC0021127It benefitted from the supercomputing resources of the National Energy Research Scientific Computing Center(NERSC),a US Department of Energy Office of Science User Facility operated under contract no.DE-AC02-05CH11231.
文摘Auxetic two-dimensional(2D)materials provide a promising platform for biomedicine,sensors,and many other applications at the nanoscale.In this work,utilizing a hypothesis-based data-driven approache,we identify multiple materials with remarkable in-plane auxetic behavior in a family of buckled monolayer 2D materials.These materials are transition metal selenides and transition metal halides with the stoichiometry MX(M=V,Cr,Mn,Fe,Co,Cu,Zn,Ag,and X=Se,Cl,Br,I).First-principles calculations reveal that the desirable auxetic behavior of these 2D compounds originates from the interplay between the buckled 2D structure and the weak metal-metal interaction determined by their electronic structures.We observe that the Poisson’s ratio is sensitive to magnetic order and the amount of uniaxial stress applied.A transition from positive Poisson’s ratio(PPR)to negative Poisson’s ratio(NPR)for a subgroup of MX compounds under large uniaxial stress is predicted.The work provides a guideline for the future design of 2D auxetic materials at the nanoscale.
基金This work was supported by the U.S.Department of Energy,Office of Science,Basic Energy Sciences,under Award#DE-SC0019275.It benefitted from the supercomputing resources of the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility operated under Contract No.DE-AC02-05CH11231,and Temple University’s HPC resources supported in part by the National Science Foundation through major research instrumentation grant number 1625061 and by the US Army Research Laboratory under contract number W911NF-16-2-0189.S.X.D.and Y.-F.Z.acknowledge support from the National Key Research and Development Program of China(No.2016YFA0202300)Strategic Priority Research Program(No.XDB30000000)+1 种基金the National Natural Science Foundation of China(No.61888102)the International Partnership Program of the Chinese Academy of Sciences(No.112111KYSB20160061).
文摘We propose a novel class of two-dimensional(2D)Dirac materials in the MX family(M=Be,Mg,Zn and Cd,X=Cl,Br and I),which exhibit graphene-like band structures with linearly-dispersing Dirac-cone states over large energy scales(0.8–1.8 eV)and ultra-high Fermi velocities comparable to graphene.Spin-orbit coupling opens sizable topological band gaps so that these compounds can be effectively classified as quantum spin Hall insulators.The electronic and topological properties are found to be highly tunable and amenable to modulation via anion-layer substitution and vertical electric field.Electronic structures of several members of the family are shown to host a Van-Hove singularity(VHS)close to the energy of the Dirac node.The enhanced density-of-states associated with these VHSs could provide a mechanism for inducing topological superconductivity.The presence of sizable band gaps,ultra-high carrier mobilities,and small effective masses makes the MX family promising for electronics and spintronics applications.
