A5019406214- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Advanced Condensed Matter Physics
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- 2D Materials and Applications
- Graphene research and applications
- Advanced Chemical Physics Studies
- Superconducting Materials and Applications
- Inorganic Chemistry and Materials
- Fullerene Chemistry and Applications
- Superconductivity in MgB2 and Alloys
- Corporate Taxation and Avoidance
- ZnO doping and properties
- Atomic and Subatomic Physics Research
- Surface and Thin Film Phenomena
- Quantum, superfluid, helium dynamics
- Diamond and Carbon-based Materials Research
- Magnetic properties of thin films
- Quantum many-body systems
- Magnetic Properties of Alloys
- Carbon Nanotubes in Composites
- Advanced Physical and Chemical Molecular Interactions
Lawrence Berkeley National Laboratory
2021-2025
University of California System
2025
Chinese Academy of Sciences
2018-2024
Institute of Physics
2018-2024
National Laboratory for Superconductivity
2019-2024
University of California, Berkeley
2022
University of Chinese Academy of Sciences
2018-2020
Czech Academy of Sciences, Institute of Physics
2019
Fudan University
2013
The study of quantum phase transitions that are not clearly associated with broken symmetry is a major effort in condensed matter physics, particularly regard to the problem high-temperature superconductivity, for which such thought underlie mechanism superconductivity itself. Here we argue putative critical point prototypical unconventional superconductor CeCoIn5 characterized by delocalization electrons transition connects two Fermi surfaces different volumes, no apparent symmetry. Drawing...
The iron-based superconductors are characterized by multiple-orbital physics where all the five Fe 3$d$ orbitals get involved. nature gives rise to various novel phenomena like orbital-selective Mott transition, nematicity and orbital fluctuation that provide a new route for realizing superconductivity. complexity of also asks disentangle relationship between orbital, spin nematicity, identify dominant ingredients dictate bulk FeSe superconductor provides an ideal platform address these...
Topological quantum materials, including topological insulators and superconductors, Dirac semimetals Weyl semimetals, have attracted much attention recently for their unique electronic structure, spin texture physical properties. Very lately, a new type of has been proposed where the Fermions emerge at boundary between electron hole pockets in phase matter, which is distinct from standard I with point-like Fermi surface. The cone this II strongly tilted related surface undergos Lifshitz...
Abstract Revelation of emerging exotic states topological insulators (TIs) for future quantum computing applications relies on breaking time-reversal symmetry and opening a surface energy gap. Here, we report the transport response Bi 2 Te 3 TI thin films in presence varying Cr dopants. By tracking magnetoconductance (MC) low doping regime observed progressive crossover from weak antilocalization (WAL) to localization (WL) as concentration increases. In high regime, however, increasing...
The transient excitonic condensate is a nonequilibrium electron–hole Bardeen–Cooper–Schrieffer state in photoexcited semiconductor and semimetal, where pairs undergo phase transition condense into single coherent quantum state. Despite numerous experimental works to realize the predicted condensation phase, evidence still remains elusive. This largely due absence of direct measurements material’s momentum-dependent electronic structure regime. Here, using time angle-resolved photoemission...
The superconducting gap symmetry is crucial in understanding the underlying superconductivity mechanism. Angle-resolved photoemission spectroscopy (ARPES) has played a key role determining unconventional superconductors. However, it been considered so far that ARPES can only measure magnitude of but not its phase; phase to be detected by other phase-sensitive techniques. Here we propose method directly detect sign ARPES. This successfully validated cuprate superconductor Bi2Sr2CaCu2O8+δ with...
High resolution laser-based angle-resolved photoemission measurements were carried out on an overdoped $Bi_2Sr_2CaCu_2O_{8+\delta}$ superconductor with a Tc of 75 K. Two Fermi surface sheets caused by bilayer splitting are clearly identified rather different doping levels: the bonding sheet corresponds to level 0.14 which is slightly underdoped while antibonding has 0.27 that heavily overdoped, giving overall 0.20 for sample. Different superconducting gap sizes two revealed first time. The...
The authors report the experimental band structure of layered 1T'-TaTe${}_{2}$ across a CDW-like phase transition and reveal existence nested quasi-one-dimensional Fermi surface in two-dimensional material.
High-quality Bi$_{2-x}$Pb$_{x}$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212) single crystals have been successfully grown by the traveling solvent floating zone technique with a wide range of Pb substitution ($x=0-0.8$). The samples are characterized transmission electron microscope (TEM) and measured high resolution laser-based angle-resolved photoemission spectroscopy (ARPES) different photon energies. A systematic evolution electronic structure superstructure has revealed for first time. shows...
Experiments reveal that the iron-based superconductor FeSe has a richer electronic structure than previously known, which may further studies into its rich physical properties and superconductivity mechanism.
Unexpected hybridization between the main band and superstructure in Bi${}_{2}$Sr${}_{2}$CaCu${}_{2}$O${}_{8+\ensuremath{\delta}}$ (Bi2212) superconductor is revealed by high-resolution laser-based angle-resolved photoemission measurements. It can be understood considering selective of bands from bilayer splitting Bi2212. These observations indicate that origin intrinsic to CuO${}_{2}$ planes. Understanding physical properties superconductivity Bi2212 needs consideration complete Fermi...
The transition of C${}_{60}$ from a molecular insulator to correlated metal is followed, upon alkali doping, by angle-resolved photoemission, which at half filling the conduction states shows appearance linearly dispersive bands.
Layered ferromagnets are thrilling materials from both a fundamental and technological point of view. VI3 is an interesting example, with complex magnetism that differentiates it the first reported Cr based layered ferromagnets. Here, we show in indirect way through Angle Resolved Photoemission Spectroscopy (ARPES) experiments, importance spin-orbit coupling setting electronic properties this material. Our light polarized photoemission measurements to ground state half-filled e'_+- doublet,...
High temperature superconductivity in cuprates is realized by doping the Mott insulator with charge carriers. A central issue how such an insulating state can evolve into a conducting or superconducting when carriers are introduced. Here, situ vacuum annealing and Rb deposition on Bi2Sr2Ca0.6Dy0.4Cu2O8+delta (Bi2212) sample surface to push its level continuously from deeply underdoped (Tc=25 K, p-0.066) near zero parent insulator, angle-resolved photoemission spectroscopy measurements...
Molecular crystals are a flexible platform to induce novel electronic phases. Due the weak forces between molecules, intermolecular distances can be varied over relatively larger ranges than interatomic in atomic crystals. On other hand, hopping terms generally small, which results narrow bands, strong correlations and heavy electrons. Here, by growing K$_x$C$_{60}$ fullerides on hexagonal layered Bi$_2$Se$_3$, we show that upon doping series undergoes Mott transition from molecular...
Superconductivity is realized by opening a gap in the superconducting state. The symmetry crucial understanding underlying superconductivity mechanism. magnitude and phase are essential fully characterizing gap. Angle-resolved photoemission spectroscopy (ARPES) has played key role determining unconventional superconductors. However, it been considered so far that ARPES can only measure of but not its phase; to be detected other phase-sensitive techniques. Here we propose new method directly...