A5047969879- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Graphene research and applications
- Iron-based superconductors research
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Corporate Taxation and Avoidance
- 2D Materials and Applications
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- Molecular Junctions and Nanostructures
- Superconductivity in MgB2 and Alloys
- Quantum many-body systems
- Diamond and Carbon-based Materials Research
- Atomic and Subatomic Physics Research
- Surface Chemistry and Catalysis
- Rare-earth and actinide compounds
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Organic and Molecular Conductors Research
- Thermal properties of materials
- Cold Atom Physics and Bose-Einstein Condensates
- Advanced Materials Characterization Techniques
Tsinghua University
2016-2025
Beijing Academy of Quantum Information Sciences
2019-2024
State Key Laboratory of Low-Dimensional Quantum Physics
2014-2022
Southern University of Science and Technology
2021
Shandong University
2020
Collaborative Innovation Center of Quantum Matter
2014-2019
Institute of Physics
2007-2016
Chinese Academy of Sciences
2005-2015
Rensselaer Polytechnic Institute
2012
National Laboratory for Superconductivity
2011
We report high transition temperature superconductivity in one unit-cell (UC) thick FeSe films grown on a Se-etched SrTiO3 (001) substrate by molecular beam epitaxy (MBE). A superconducting gap as large 20 meV and the magnetic field induced vortex state revealed situ scanning tunneling microscopy (STM) suggest that of 1 UC could occur around 77 K. The control transport measurement shows onset is well above 50 Our work not only demonstrates powerful way for finding new superconductors raising...
Theoretical studies predicted that doping graphene with nitrogen can tailor its electronic properties and chemical reactivity. However, experimental investigations are still limited because of the lack synthesis techniques deliver a reasonable quantity. We develop here novel method for one-pot direct N-doped via reaction tetrachloromethane lithium nitride under mild conditions, which renders fabrication in gram scale. The distinct structure perturbation induced by incorporation network is...
We report direct imaging of standing waves the nontrivial surface states topological insulator Bi2Te3 using a scanning tunneling microscope. The interference fringes are caused by scattering off Ag impurities and step edges on Bi2Te3(111) surface. By studying voltage-dependent wave patterns, we determine energy dispersion E(k), which confirms Dirac cone structure states. further show that, very different from conventional states, backscattering nonmagnetic is completely suppressed. absence...
Intrinsic magnetic topological insulator (TI) is a stoichiometric compound possessing both inherent order and electronic states. Such material can provide shortcut to various novel quantum effects but remains elusive experimentally so far. Here, we report the experimental realization of high-quality thin films an intrinsic TI---MnBi$_2$Te$_4$---by alternate growth Bi$_2$Te$_3$ quintuple-layer MnTe bilayer with molecular beam epitaxy. The shows archetypical Dirac surface states in...
Three-dimensional topological insulators (TIs) are characterized by their nontrivial surface states, in which electrons have spin locked at a right angle to momentum under the protection of time-reversal symmetry. The topologically ordered phase TIs does not break any interplay between order and symmetry breaking, such as that observed superconductivity, can lead new quantum phenomena devices. We fabricated superconducting TI/superconductor heterostructure growing dibismuth triselenide...
Scanning tunneling spectroscopy suggests an orbital ordering mechanism for electron pairing in iron-based superconductor.
We report the direct observation of Landau quantization in Bi2Se3 thin films by using a low-temperature scanning tunneling microscope. In particular, we discovered zeroth level, which is predicted to give rise half-quantized Hall effect for topological surface states. The existence discrete levels (LLs) and suppression LLs impurities strongly support 2D nature These observations may eventually lead realization quantum insulators.
Topological insulators (TI) are a new class of quantum materials with insulating bulk enclosed by topologically protected metallic boundaries. The surface states three-dimensional TIs have spin helical Dirac structure, and robust against time reversal invariant perturbations. This extraordinary property is notably exemplified the absence backscattering nonmagnetic impurities weak antilocalization (WAL) fermions. Breaking symmetry (TRS) magnetic element doping predicted to create variety...
We report a transport study of ultrathin Bi${}_{2}$Se${}_{3}$ topological insulators with thickness from one quintuple layer to six layers grown on sapphire by molecular beam epitaxy. At low temperatures, the film resistance increases logarithmically decreasing temperature, revealing an insulating ground state. The behavior becomes more pronounced in thinner films. sharp increase magnetic field, however, indicates existence weak antilocalization originated protection. show that this unusual...
The breaking of time reversal symmetry in topological insulators may create previously unknown quantum effects. We observed a magnetic phase transition Cr-doped Bi2(SexTe1-x)3 insulator films grown by means molecular beam epitaxy. Across the critical point, is revealed through both angle-resolved photoemission measurements and density functional theory calculations. present strong evidence that bulk band topology fundamental driving force for transition. tunable properties this system are...
Cooling to see the effects of disorder In sufficiently strong external magnetic fields, thin superconducting films typically become insulating. The presence can affect this phase transition. Theorists have proposed that cause so-called Griffiths singularity, where behavior system is determined by a small number islands form above critical field. Xing et al. observed signature such singularity in gallium analyzing transport data taken at very low temperatures (see Perspective Markovic)....
The superexchange mechanism in cobalt phthalocyanine (CoPc) thin films was studied by a low temperature scanning tunneling microscope. CoPc molecules were found to form one-dimensional antiferromagnetic chains the film. Collective spin excitations individual molecular measured with spin-flip associated inelastic electron spectroscopy. By spatially mapping spin-flipping channels submolecular precision, we are able explicitly identify specific orbitals that mediate interaction between molecules.
Tunneling spectra for individual atoms and dimers of Mn Cr adsorbed on superconducting Pb thin films were measured by a low temperature scanning tunneling microscope. Multiple-resonance structures within the gap adsorbates resolved interpreted as magnetic impurity-induced bound states associated with different scattering channels. The experiment demonstrates spectroscopic approach to characterizing spin exploring competition between superconductivity magnetism at nanometer scale.
Manipulating the Kondo effect by quantum confinement has been achieved placing magnetic molecules on silicon-supported nanostructures. The resonance of individual manganese phthalocyanine (MnPc) adsorbed top Pb islands was studied scanning tunneling spectroscopy. Oscillating temperatures as a function film thickness were observed and attributed to formation thickness-dependent quantum-well states in host islands. present approach provides technologically feasible way for single spin...
We report the experimental observation of Landau quantization molecular beam epitaxy grown Sb2Te3 thin films by a low-temperature scanning tunneling microscope. Different from all reported systems, in topological insulator is not sensitive to intrinsic substitutional defects films. As result, nearly perfect linear energy dispersion surface states as 2D massless Dirac fermion system achieved. demonstrate that 4 quintuple layers are thickness limit for film being 3D insulator. The mechanism...
High-quality Sb2Te3 films are obtained by molecular beam epitaxy on a graphene substrate and investigated in situ scanning tunneling microscopy spectroscopy. Intrinsic defects responsible for the natural p-type conductivity of identified to be Sb vacancies Sb(Te) antisites agreement with first-principles calculations. By minimizing defect densities, coupled transfer doping substrate, Fermi level thin can tuned over entire range bulk band gap. This establishes necessary condition explore...
We report on molecular beam epitaxy growth of stoichiometric and superconducting FeSe crystalline thin films double-layer graphene. Layer-by-layer high-quality has been achieved in a well-controlled manner by using Se-rich condition, which allow us to investigate the thickness-dependent superconductivity FeSe. In situ low-temperature scanning tunneling spectra reveal that local gap quasiparticle density states is visible down two triple layers for minimum measurement temperature 2.2 K,...