A5100459856- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Topological Materials and Phenomena
- Superconducting Materials and Applications
- Advanced Chemical Physics Studies
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Iron-based superconductors research
- 2D Materials and Applications
- High-pressure geophysics and materials
- Cold Atom Physics and Bose-Einstein Condensates
- Graphene research and applications
- Laser-Matter Interactions and Applications
- Magnetic properties of thin films
- Inorganic Fluorides and Related Compounds
- Rare-earth and actinide compounds
- Quantum optics and atomic interactions
- Atomic and Subatomic Physics Research
- Surface and Thin Film Phenomena
- Origins and Evolution of Life
- Quantum and electron transport phenomena
- Quantum, superfluid, helium dynamics
- Magnetic Properties and Applications
- Orbital Angular Momentum in Optics
- Photorefractive and Nonlinear Optics
University of Wisconsin–Madison
2024-2025
Nanjing University of Science and Technology
2024
Guilin University of Electronic Technology
2016-2024
Institute of Physics
2008-2023
Bielefeld University
2020-2023
Shanghai Jiao Tong University
2016-2023
National Laboratory for Superconductivity
2008-2023
Chinese Academy of Sciences
2008-2023
Collaborative Innovation Center of Advanced Microstructures
2019-2023
Nanjing University
2020-2023
In magnetic topological insulators (TIs), the interplay between order and nontrivial topology can induce fascinating quantum phenomena, such as anomalous Hall effect, chiral Majorana fermions axion electrodynamics. Recently, a great deal of attention has been focused on intrinsic TIs, where disorder effects be eliminated to large extent, which is expected facilitate emergence phenomena. despite intensive efforts, experimental evidence surface states (SSs) remains elusive. Here, by combining...
The design and performance of the first vacuum ultraviolet (VUV) laser-based angle-resolved photoemission (ARPES) system are described. VUV laser with a photon energy 6.994 eV bandwidth 0.26 meV is achieved from second harmonic generation using novel nonlinear optical crystal KBe2BO3F2. new ARPES exhibits superior performance, including superhigh resolution better than 1 meV, high momentum resolution, flux, much enhanced bulk sensitivity, which demonstrated measurements on typical...
In high-temperature superconductivity, the process that leads to formation of Cooper pairs, fundamental charge carriers in any superconductor, remains mysterious. We used a femtosecond laser pump pulse perturb superconducting Bi(2)Sr(2)CaCu(2)O(8+δ) and studied subsequent dynamics using time- angle-resolved photoemission infrared reflectivity probes. Gap quasiparticle population revealed marked dependencies on both excitation density crystal momentum. Close d-wave nodes, gap was sensitive...
The physical property investigation (like transport measurements) and ultimate application of the topological insulators usually involve surfaces that are exposed to ambient environment (1 atm room temperature). One critical issue is how surface state will behave under such conditions. We report high resolution angle-resolved photoemission measurements directly probe prototypical insulators, Bi 2 Se 3 Te , upon exposing various environments. find order robust even when air at temperature....
The significant progress in angle-resolved photoemission spectroscopy (ARPES) last three decades has elevated it from a traditional band mapping tool to precise probe of many-body interactions and dynamics quasiparticles complex quantum systems. recent developments deep ultraviolet (DUV, including vacuum ultraviolet) laser-based ARPES have further pushed this technique new level. In paper, we review some latest DUV systems, the super-high energy momentum resolution ARPES, spin-resolved...
Revealing spin-orbit coupling in a cuprate Strong between the spin and orbital degrees of freedom is crucial generating exotic band structure topological insulators. The combination with electronic correlations could lead to effects; however, these two types interactions are rarely found be strong same material. Gotlieb et al. used spin- angle-resolved photoemission spectroscopy map out texture Bi2212. Surprisingly, they signatures spin-momentum locking, not unlike that seen Thus, addition...
We propose and demonstrate a novel scheme to produce ultrashort ultrastable MeV electron beam. In this scheme, the beam produced in photocathode radio frequency (rf) gun first expands under its own Coulomb force with which positive energy chirp is imprinted longitudinal phase space. The then sent through double bend achromat dispersion where electrons at bunch tail lower energies follow shorter paths thus catch up head, leading compression. show that optimized parameter sets, whole path from...
Abstract A material’s magnetic state and its dynamics are of great fundamental research interest also at the core a wide plethora modern technologies. However, reliable access to magnetization in materials devices on technologically relevant ultrafast timescale, under realistic device-operation conditions, remains challenge. Here, we demonstrate method terahertz (THz) magnetometry, which gives direct (sub-)picosecond even encapsulated or contact-free fashion, fully calibrated manner, ambient...
The extracted pairing interactions responsible for high-temperature superconductivity lead to a clear discrimination among theories.
Abstract In low-dimensional systems with strong electronic correlations, the application of an ultrashort laser pulse often yields novel phases that are otherwise inaccessible. The central challenge in understanding such phenomena is to determine how dimensionality and many-body correlations together govern pathway a non-adiabatic transition. To this end, we examine layered compound, 1 T -TiSe 2 , whose three-dimensional charge-density-wave (3D CDW) state also features exciton condensation...
Laser-based angle-resolved photoemission measurements with superhigh resolution have been carried out on an optimally doped ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8}$ high temperature superconductor. New energy features at $\ensuremath{\sim}115\text{ }\text{ }\mathrm{meV}$ and $\ensuremath{\sim}150\text{ }\mathrm{meV}$, in addition to the prominent $\ensuremath{\sim}70\text{ one, are found develop nodal electron self-energy superconducting state. These features,...
We reveal an ultrafast purely electronic phase transition in \TNS, which is a plausible excitonic insulator, after excited by infrared laser pulse. Specifically, the order parameter of strong electron-hole binding shrinks with enhancing pump pulse, and above critical fluence, photo-excited semimetallic state experimentally identified absence structural transition. In addition, bare valence conduction bands also effective exciton energy \TNS~are determined. These findings detailed analysis...
The ultrafast electronic structures of the charge density wave material 1T-TiSe_{2} were investigated by high-resolution time- and angle-resolved photoemission spectroscopy. We found that quasiparticle populations drove phase transitions in within 100 fs after photoexcitation, a metastable metallic state, which was significantly different from equilibrium normal phase, evidenced far below transition temperature. Detailed pump-fluence-dependent experiments revealed photoinduced state result...
In this paper, the sub-wavelength transverse displacement of photonic spin Hall effect (PSHE) is significantly enhanced by surface exciton polariton (SEP) for application in gas sensing. The 14.4 times wavelength incident light achieved with SEP PSHE, which about 3 that plasmon resonance PSHE. A sensor based on PSHE proposed detection SO 2 , and refractive index sensitivity 6320.4 µ m/RIU obtained range from 1.00027281 to 1.00095981. These results undoubtedly demonstrate be a promising...
Abstract To conserve copper and extend the working life of layer, Ni15 was used as a transition layer in preparation copper-steel composites via laser cladding. Cu mixed with 5%, 10%, 15%, 20%, 25% WC-12Ni powder, cladding layers varying compositions were prepared using coaxial powder feeding. The microstructure tribological properties analyzed optical microscopy (OM), scanning electron (SEM), energy-dispersive spectroscopy (EDS). results indicate that composite coating is primarily composed...
An up to 40% relaxed N-polar InGaN pseudosubstrate was obtained by a multistep in situ porosification technique on the GaN template using metal–organic chemical vapor deposition (MOCVD) method. InaGa1–aN/InbGa1–bN/GaN superlattice (SL) layer (SLA) with higher composition of InaGa1–aN (a = 15.2%) compared InbGa1–bN (b 8.4%) porosified and coalesced thin layer. Following coalescence layer, an 80 nm-thick InxGa1–xN/InyGa1–yN/GaN SL (SLB1) x 13% y 9% deposited as second porous similarly Finally,...
We present technical specifications for a high resolution time- and angle-resolved photoemission spectroscopy setup based on hemispherical electron analyzer cavity-dumped solid state Ti:sapphire laser used to generate pump probe beams, respectively, at 1.48 5.93 eV. The pulse repetition rate can be tuned from 209 Hz 54.3 MHz. Under typical operating settings the system has an overall energy of 23 meV, momentum 0.003 Å−1, time 310 fs. illustrate capabilities with representative data cuprate...
We use time- and angle-resolved photoemission spectroscopy to characterize the dynamics of energy gap in superconducting Bi2Sr2CaCu2O8+delta (Bi2212). Photoexcitation drives system into a nonequilibrium pseudogap state: Near Brillouin zone diagonal (inside normal-state Fermi arc), completely closes for pump fluence beyond F = 15 {\mu}J/cm^2; toward face (outside it remains open at least 24 {\mu}J/cm^2. This strongly anisotropic response may indicate multiple competing ordering tendencies...
We present the development of a time- and angle-resolved photoemission spectroscopy based on Yb-based femtosecond laser hemispherical electron analyzer. The energy pump photon is tunable between 1.4 1.9 eV, pulse duration around 30 fs. use KBe2BO3F2 nonlinear optical crystal to generate probe pulses, which up 6.7 obtain an overall time resolution 1 ps 18 meV. In addition, β-BaB2O4 crystals are used alternative pulses at 6.05 giving 130 fs 19 illustrate performance system with representative...
We use time- and angle-resolved photoemission to measure the nodal nonequilibrium electronic states in various dopings of Bi${}_{2}$Sr${}_{2}$CaCu${}_{2}$O${}_{8+\ensuremath{\delta}}$. find that initial pump-induced transient signal these ungapped is strongly affected by onset superconducting gap at ${T}_{c}$, pairing fluctuations ${T}_{p}$, pseudogap ${T}^{*}$. Moreover, ${T}_{p}$ marks a suggestive threshold fluence-dependent signal, with appearance critical fluence below corresponds...
UV‐ranged micro‐LEDs are being explored for numerous applications due to their high stability and power efficiency. However, previous reports have shown reduced external quantum efficiency (EQE) increased leakage current the increase in surface‐to‐volume ratio with a decrease micro‐LED size. Herein, size‐related performance UV‐A micro‐LEDs, ranging from 8 × 100 μm 2 , is studied. These devices exhibit implementation of atomic layer deposition‐based sidewall passivation. A systematic EQE...