An intrinsic magnetic topological insulator(TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel ...An intrinsic magnetic topological insulator(TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel topological quantum effects but remained elusive experimentally for a long time. Here we report the experimental realization of thin films of an intrinsic magnetic TI, MnBi2Te4, by alternate growth of a Bi2Te3 quintuple layer and a MnTe bilayer with molecular beam epitaxy. The material shows the archetypical Dirac surface states in angle-resolved photoemission spectroscopy and is demonstrated to be an antiferromagnetic topological insulator with ferromagnetic surfaces by magnetic and transport measurements as well as first-principles calculations. The unique magnetic and topological electronic structures and their interplays enable the material to embody rich quantum phases such as quantum anomalous Hall insulators and axion insulators at higher temperature and in a well-controlled way.展开更多
We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that t...We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that the superconducting gap(△s)in nano-sized Pb islands is significantly enhanced from the one in bulk Pb,while there is no essential change in superconducting transition temperature Tc,giving rise to a larger BCS ratio 2△s/kBTc^8.31 and implying stronger electron-phonon coupling.The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3.As the superconducting gap is totally suppressed under applied magnetic field,the Coulomb gap with apparent V-shape emerges.Moreover,the size of Coulomb gap(Ac)depends on the lateral size of Pb islands(R)with △c-1/R^035,indicating that quantum size effect can significantly influence electronic correlations.Our experimental results shall shed important light on the interplay among superconductivity,quantum size effect and correlations in nano-sized strong-coupling superconductors.展开更多
基金Supported by the Ministry of Science and Technology of Chinathe National Science Foundation of Chinathe Beijing Advanced Innovation Center for Future Chip(ICFC)
文摘An intrinsic magnetic topological insulator(TI) is a stoichiometric magnetic compound possessing both inherent magnetic order and topological electronic states. Such a material can provide a shortcut to various novel topological quantum effects but remained elusive experimentally for a long time. Here we report the experimental realization of thin films of an intrinsic magnetic TI, MnBi2Te4, by alternate growth of a Bi2Te3 quintuple layer and a MnTe bilayer with molecular beam epitaxy. The material shows the archetypical Dirac surface states in angle-resolved photoemission spectroscopy and is demonstrated to be an antiferromagnetic topological insulator with ferromagnetic surfaces by magnetic and transport measurements as well as first-principles calculations. The unique magnetic and topological electronic structures and their interplays enable the material to embody rich quantum phases such as quantum anomalous Hall insulators and axion insulators at higher temperature and in a well-controlled way.
基金the National Natural Science Foundation under Grant Nos.11674191 and 11825404the National Key Program for S&T Research and Development under Grant No No.2016YFA0301002the Beijing Advanced Innovation Center for Future Chip(ICFC).W.L.was also supported by Beijing Young Talents Plan.
文摘We report high-resolution scanning tunneling microscopy(STM)study of nano-sized Pb islands grown on SrTiO3,where three distinct types of gaps with different energy scales are revealed.At low temperature,we find that the superconducting gap(△s)in nano-sized Pb islands is significantly enhanced from the one in bulk Pb,while there is no essential change in superconducting transition temperature Tc,giving rise to a larger BCS ratio 2△s/kBTc^8.31 and implying stronger electron-phonon coupling.The stronger coupling can originate from the interface electron-phonon interactions between Pb islands and SrTiO3.As the superconducting gap is totally suppressed under applied magnetic field,the Coulomb gap with apparent V-shape emerges.Moreover,the size of Coulomb gap(Ac)depends on the lateral size of Pb islands(R)with △c-1/R^035,indicating that quantum size effect can significantly influence electronic correlations.Our experimental results shall shed important light on the interplay among superconductivity,quantum size effect and correlations in nano-sized strong-coupling superconductors.
基金This work is financially supported by the National Key Research and Development Program of China （No. 2017YFA0303303）, the National Natural Science Foundation of China （No. 51661135024）, and the Beijing Advanced Innovation Center for Future Chip （ICFC）.
