The search for new materials with Dirac points has been a fascinating subject of condensed matter physics.Here we first report the growth and band structure of HfGe_(0.92)Te single crystals featuring three different t...The search for new materials with Dirac points has been a fascinating subject of condensed matter physics.Here we first report the growth and band structure of HfGe_(0.92)Te single crystals featuring three different types of Dirac points.HfGe_(0.92)Te crystallizes in a nonsymmorphic tetragonal space group P4/nmm(No.129),having a square Ge-atom plane with vacancies of about 8%.Using angle-resolved photoemission spectroscopy(ARPES),the Dirac nodal line composed of conventional Dirac points vulnerable to spin-orbit coupling(SOC)is observed,accompanied by robust Dirac points protected by the nonsymmorphic symmetry against SOC and vacancies.In particular,spin-orbit Dirac points(SDPs)originating from the surface formed under significant SOC could exist based on ARPES and calculations.Quasi-two-dimensional(quasi-2D)characteristics are confirmed by angular-resolved magnetoresistance.HfGe_(0.92)Te bulk crystals can be easily exfoliated to flakes with a thickness of approximately 5 nm for the quasi-2D nature.Thus,HfGe_(0.92)Te provides a good platform to explore exotic topological phases or topological properties with three different types of Dirac points,which is a potential candidate to achieve novel 2D SDPs.展开更多
基金partially supported by the National Natural Science Foundation of China(Grant Nos.51832010,51902055,11925408,12005251,and 11921004)National Key Research and Development Program of China(Grant Nos.2018YFE0202602,2018YFA0305700,and 2017YFA0302902)。
文摘The search for new materials with Dirac points has been a fascinating subject of condensed matter physics.Here we first report the growth and band structure of HfGe_(0.92)Te single crystals featuring three different types of Dirac points.HfGe_(0.92)Te crystallizes in a nonsymmorphic tetragonal space group P4/nmm(No.129),having a square Ge-atom plane with vacancies of about 8%.Using angle-resolved photoemission spectroscopy(ARPES),the Dirac nodal line composed of conventional Dirac points vulnerable to spin-orbit coupling(SOC)is observed,accompanied by robust Dirac points protected by the nonsymmorphic symmetry against SOC and vacancies.In particular,spin-orbit Dirac points(SDPs)originating from the surface formed under significant SOC could exist based on ARPES and calculations.Quasi-two-dimensional(quasi-2D)characteristics are confirmed by angular-resolved magnetoresistance.HfGe_(0.92)Te bulk crystals can be easily exfoliated to flakes with a thickness of approximately 5 nm for the quasi-2D nature.Thus,HfGe_(0.92)Te provides a good platform to explore exotic topological phases or topological properties with three different types of Dirac points,which is a potential candidate to achieve novel 2D SDPs.
