A5052830575- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Corporate Taxation and Avoidance
- Advanced Condensed Matter Physics
- Intellectual Capital and Performance Analysis
- Rare-earth and actinide compounds
- Advanced Fiber Laser Technologies
- Superconductivity in MgB2 and Alloys
- Advanced Thermoelectric Materials and Devices
- Electronic and Structural Properties of Oxides
- Quantum optics and atomic interactions
- Photonic Crystal and Fiber Optics
- Spectroscopy and Laser Applications
- Gas Sensing Nanomaterials and Sensors
- High-pressure geophysics and materials
- Advanced Photocatalysis Techniques
- Semiconductor Lasers and Optical Devices
- Theoretical and Computational Physics
- Catalytic Processes in Materials Science
- 2D Materials and Applications
- Solid State Laser Technologies
- Amyloidosis: Diagnosis, Treatment, Outcomes
- Magnetic Properties of Alloys
- Advanced battery technologies research
Beihang University
2023-2024
Hefei National Center for Physical Sciences at Nanoscale
2005-2015
University of Science and Technology of China
2005-2015
Collaborative Innovation Center of Advanced Microstructures
2015
Microscale (United States)
2006
The in-plane resistivity $\ensuremath{\rho}$ and thermal conductivity $\ensuremath{\kappa}$ of the FeAs-based superconductor ${\mathrm{KFe}}_{2}{\mathrm{As}}_{2}$ single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior $\ensuremath{\rho}(T)\ensuremath{\sim}{T}^{1.5}$ at ${H}_{{c}_{2}}=5\text{ }\text{ }\mathrm{T}$, development a Fermi liquid state with $\ensuremath{\rho}(T)\ensuremath{\sim}{T}^{2}$ when further increasing field. This suggests field-induced quantum...
While the parent compounds of cuprate high temperature superconductors (high-Tc's) are Mott insulators, iron-pnictide high-Tc's in vicinity a metallic spin density wave (SDW) state, which highlights difference between these two families. However, insulating were identified for newly discovered KxFe2-ySe2. This raises an intriguing question as to whether iron-based could be viewed doped insulators like cuprates. Here we report angle-resolved photoemission spectroscopy (ARPES) evidence and one...
The unconventional superconductivity in the newly discovered iron-based superconductors is intimately related to its multiband/multiorbital nature. Here we report comprehensive orbital characters of low-energy three-dimensional electronic structure BaFe${}_{1.85}$Co${}_{0.15}$As${}_{2}$ by studying polarization and photon-energy dependence angle-resolved photoemission data. While distributions ${d}_{\mathit{xz}}$, ${d}_{\mathit{yz}}$, ${d}_{3{z}^{2}\ensuremath{-}{r}^{2}}$ orbitals agree with...
Although a nodeless superconducting gap has been observed on the large Fermi pockets around zone corner in K${}_{x}$Fe${}_{2\ensuremath{-}y}$Se${}_{2}$, whether its pairing symmetry is $s$ wave or $d$ still under intense debate. Here we report an isotropic distribution small electron pocket $Z$ point which favors $s$-wave symmetry.
The electronic structure of a new charge-density-wave/ superconductor system, 1T-CuxTiSe2, has been studied by photoemission spectroscopy. A correlated semiconductor band is revealed for the undoped case. With Cu doping, charge density wave suppressed raising chemical potential, while superconductivity enhanced enhancement states. Moreover, strong scattering at high doping might be responsible suppression in that regime.
The three-dimensional band structure and superconducting gap of Ba0.6K0.4Fe2As2 are studied with angle-resolved photoemission spectroscopy. In contrast previous results, we have identified three holelike Fermi surface sheets near the zone center sizable out-of-plane or kz dispersion. on certain shows significant dependence. Moreover, sizes different at same momentum for two bands spatial symmetries (one odd, one even). Our results further reveal orbital-dependent in iron pnictides, which...
The electronic structure of NaFeAs is studied with angle-resolved photoemission spectroscopy on high quality single crystals. Large portions the band start to shift around structural transition temperature and smoothly evolve as lowers through spin density wave transition. Moreover, folding due magnetic order emerges slightly above Our observation provides direct evidence that transitions share same origin could both be driven by reconstruction in Fe-based superconductors instead Fermi...
The nature of the spin-density wave (SDW) and its relation with superconductivity are crucial issues in newly discovered iron-pnictide superconductors. Particularly, it is unclear whether superconducting phase SDW truly exclusive from each other. We here report splittings band structures Sr1-xKxFe2As2 (x=0, 0.1, 0.18), their unusual doping dependence. Our data on single crystalline samples prove that could coexist iron pnictides.
The electronic structure of $\ensuremath{\alpha}{\text{-Fe}}_{1.06}\text{Te}$ is studied with angle-resolved photoemission spectroscopy. We show that there substantial spectral weight around $\ensuremath{\Gamma}$ and X, line shapes are intrinsically broad in the paramagnetic state. magnetic transition characterized by a massive transfer over an energy range as large bandwidth, which even exhibits hysteresis loop marks strong first-order transition. Coherent quasiparticles emerge magnetically...
The electronic structure of LaFeAsO, a parent compound iron-arsenic superconductors, is studied by angle-resolved photoemission spectroscopy. By examining its dependence on photon energy, polarization, and sodium dosing, both the bulk surface contributions are identified. We find that band moves toward high binding energies below structural transition temperature, shifts smoothly across spin-density-wave about 25 meV. Our data suggest reconstruction may play crucial role in transitions. For...
The in-plane thermal conductivity of iron-based superconductor ${\mathrm{RbFe}}_{2}{\mathrm{As}}_{2}$ single crystal $({T}_{c}\ensuremath{\approx}$ 2.1 K) was measured down to 100 mK. In zero field, the observation a significant residual linear term ${\ensuremath{\kappa}}_{0}/T$ = 0.65 mW ${\mathrm{K}}^{\ensuremath{-}2}$ ${\mathrm{cm}}^{\ensuremath{-}1}$ provides clear evidence for nodal superdonducting gap. field dependence is similar that its sister compound...
The structure and electronic property at the cleaved (001) surfaces of newly discovered pnictide superconductors ${\text{BaFe}}_{2\ensuremath{-}x}{\text{Co}}_{x}{\text{As}}_{2}$ with $x$ ranging from 0 to 0.32 are systematically investigated by scanning tunneling microscopy. A $\sqrt{2}\ifmmode\times\else\texttimes\fi{}\sqrt{2}$ surface is revealed dominate for all compounds identified be Ba layer half atoms lifted off combination theoretical simulation. Charge inhomogeneity observed this...
The thermal conductivity of iron-based superconductor CsFe${}_{2}$As${}_{2}$ single crystal (${T}_{c}=1.81$ K) was measured down to 50 mK. A significant residual linear term ${\ensuremath{\kappa}}_{0}/T=1.27$ mW K${}^{\ensuremath{-}2}$ cm${}^{\ensuremath{-}1}$ is observed in zero magnetic field, which about 1/10 the normal-state value upper critical field ${H}_{c2}$. In low ${\ensuremath{\kappa}}_{0}/T$ increases rapidly with field. normalized ${\ensuremath{\kappa}}_{0}/T(H)$ curve for our...
We report the high-resolution angle-resolved photoemission spectroscopy studies of electronic structure ${\text{EuFe}}_{2}{\text{As}}_{2}$. The paramagnetic state data are found to be consistent with density-functional calculations. In antiferromagnetic ordering Fe, our results show that band splitting, folding, and hybridization evolve temperature, which cannot explained by a simple folding picture. Detailed measurements reveal tiny electron Fermi pocket hole formed near...
The electronic structure of ${\text{BaTi}}_{2}$${\text{As}}_{2}O$, a parent compound the newly discovered titanium-based oxypnictide superconductors, is studied by angle-resolved photoemission spectroscopy and first-principles calculation. experimental shows multiorbital nature three-dimensional character, which consistent with calculated results. An anomalous temperature-dependent spectral weight redistribution broad line shape indicate incoherent function. At density-wave-like transition...
Magnetic and transport properties of polycrystalline Gd1-xSrxCoO3-δ (x = 0.10−0.70) annealed under the oxygen pressure 165 atm at 500 °C are systematically investigated. Cluster-glass behavior is observed in low doping range, while a ferromagnetic transition occurs high level. Transport measurements indicate insulator-like for samples with x ≤ 0.30, an insulator−metal around 0.35, metallic higher samples. However, large deficiency leads to re-entrance state ≥ 0.60. The annealing procedure...
A high-power, coherent, and frequency-stable 770 nm laser is vital for experiments in atom physics. This letter presents an all-fiber based on second harmonic generation (SHG) frequency-stabilized using the R2 absorption line of H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> C xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> N. stabilization technique utilizes acoustic effect to generate a dispersion-like error signal with steep...
Magnetotransport properties are systematically investigated on Ca3Co4O9 + δ single crystals with different carrier concentrations changed by oxygen content. The in-plane resistivity decreases rapidly increasing concentration. Large negative magnetoresistance was observed in all the crystals. A magnetic-field–driven sign change of slope at 25 K and a magnetic-dependent energy gap range 20–60 highly doped crystals, while they absent low concentrations. In addition, thermally activated induced...
The misfit oxide, Bi2Ba1.3K0.6Co2.1O7.94, made of alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO2 layers, was studied by angle-resolved photoemission spectroscopy, revealing the electronic structure a highly strained oxide interface. We found that low-energy states are confined within individual sides interface, but scattered incommensurate crystal field from other side. Furthermore, high strain on rocksalt layer induces large charge transfer to layer, novel effect,...
The thermal conductivity of optimally doped NaFe$_{0.972}$Co$_{0.028}$As ($T_c \sim$ 20 K) and overdoped NaFe$_{0.925}$Co$_{0.075}$As 11 single crystals were measured down to 50 mK. No residual linear term $\kappa_0/T$ is found in zero magnetic field for both compounds, which an evidence nodeless superconducting gap. Applying up $H$ = 9 T ($\approx H_{c2}/4$) does not noticeably increase NaFe$_{1.972}$Co$_{0.028}$As, consistent with multiple isotropic gaps similar magnitudes....
Angular-dependent in-plane magnetoresistance (AMR) for single crystal $Na_{0.34}(H_3O)_{0.15}CoO_2$ with charge ordering is studied systematically. The anisotropic shows a twofold symmetry at high temperature rotating H in the Co-O plane, while sixfold below certain ($T_\rho$). At $T_\rho$, of AMR changes from to fourfold magnetic field (H) plane consisting current and c-axis. variation arises subtle spin structure. These results give direct evidence itinerant electrons directly coupled...
The out-of-plane resistivity ($\rho_c$) and magnetoresistivity (MR) are studied in antiferromangetic (AF) $Nd_{2-x}Ce_xCuO_{4}$ single crystals, which have three types of noncollinear spin structures. apparent signatures observed $\rho_c(T)$ measured at the zero-field 14 T structure transitions, giving a definite evidence for itinerant electrons directly coupled to localized spins. One striking feature is an anisotropy MR with fourfold symmetry upon rotating external field (B) within ab...