A5061109291- Topological Materials and Phenomena
- 2D Materials and Applications
- Graphene research and applications
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- High Entropy Alloys Studies
- Electronic and Structural Properties of Oxides
- Crystal Structures and Properties
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Advanced Thermoelectric Materials and Devices
- Phase-change materials and chalcogenides
- Magnetic Field Sensors Techniques
- Chalcogenide Semiconductor Thin Films
- Organic and Molecular Conductors Research
- High-Temperature Coating Behaviors
- Heusler alloys: electronic and magnetic properties
- Molecular Junctions and Nanostructures
- Advanced Semiconductor Detectors and Materials
- Inorganic Chemistry and Materials
- Surface and Thin Film Phenomena
- Magnetic Properties of Alloys
- Advanced Chemical Physics Studies
Pennsylvania State University
2020-2024
Clinique Victor Hugo
2022
Northwestern University
2019
Harbin Institute of Technology
2018-2019
Weyl semimetals (WSM) have been extensively studied due to their exotic properties such as topological surface states and anomalous transport phenomena. Their band structure topology is usually predetermined by material parameters can hardly be manipulated once the formed. unique appear at very low temperature, which sets challenges for practical device applications. In this work, we demonstrate a way modify via weak magnetic field in ferromagnetic semimetal, Co2MnAl, room temperature. We...
Nonlinear Hall effect (NLHE) is a new type of with wide application prospects. Practical device applications require strong NLHE at room temperature (RT). However, previously reported NLHEs are all low-temperature phenomena except for the surface TaIrTe4. Bulk RT highly desired due to its ability generate large photocurrent. Here, we show spin-valley locked Dirac state in BaMnSb2 can bulk RT. In microscale devices, observe typical signature an intrinsic NLHE, i.e. transverse voltage...
The discovery of Weyl semimetals (WSMs) has fueled tremendous interest in condensed matter physics. WSMs require breaking either inversion symmetry (IS) or time-reversal (TRS); they can be categorized into type-I and type-II WSMs, characterized by un-tilted strongly tilted cones respectively. Type-I with IS TRS have been realized experimentally, but TRS-breaking WSM still remains elusive. In this article, we report an ideal only one pair nodes observed the antiferromagnetic topological...
Abstract Topological kagome magnets RMn 6 Sn (R = rare earth element) attract numerous interests due to their non-trivial band topology and room-temperature magnetism. Here, we report a high entropy version of magnet, (Gd 0.38 Tb 0.27 Dy 0.20 Ho 0.15 )Mn . Such material exhibits multiple spin reorientation transitions, which is not seen in all the related parent compounds can be understood terms competing magnetic interactions enabled by entropy. Furthermore, also observed an intrinsic...
Magnetism in topological materials creates phases exhibiting quantized transport phenomena with potential technological applications. The emergence of such relies on strong interaction between localized spins and the bands, consequent formation an exchange gap. However, this remains experimentally unquantified intrinsic magnetic materials. Here, is quantified MnBi2 Te4 , a insulator antiferromagnetism. This achieved by optically exciting Bi-Te p states comprising bulk bands interrogating Mn...
The study of high-entropy materials has attracted enormous interest since they could show new functional properties that are not observed in their related parent phases. Here, we report single crystal growth, structure, thermal transport, and magnetic property studies on a novel oxide with the spinel structure (MgMnFeCoNi)Al2O4. We have successfully grown high-quality crystals this using optical floating zone growth technique for first time. sample was confirmed to be phase pure x-ray...
Abstract Rare-earth monopnictides are a family of materials simultaneously displaying complex magnetism, strong electronic correlation, and topological band structure. The recently discovered emergent arc-like surface states in these have been attributed to the multi-wave-vector antiferromagnetic order, yet direct experimental evidence has elusive. Here we report observation non-collinear order with multiple modulations using spin-polarized scanning tunneling microscopy. Moreover, discover...
Dirac and Weyl semimetals are a central topic of contemporary condensed matter physics, the discovery new compounds with Dirac/Weyl electronic states is crucial to advancement topological materials quantum technologies. Here we show widely applicable strategy that uses high configuration entropy engineer relativistic states. We take AMnSb
How disorder affects magnetic ordering is always an intriguing question, and it becomes even more interesting in the recently rising high entropy oxides due to extremely density. However, lack of high-quality single crystal samples, strong compositional effect on transition has not been deeply investigated. In this work, we have successfully synthesized crystalline spinel ferrites (Mg
Abstract Proposed mechanisms for large intrinsic anomalous Hall effect (AHE) in magnetic topological semimetals include diverging Berry curvatures of Weyl nodes, anticrossing nodal rings or points non-trivial bands. Here we demonstrate that a half-topological semimetal (HTS) state near critical point can provide an alternative mechanism AHE via systematic studies on antiferromagnetic (AFM) half-Heusler compound TbPdBi. We not only observe with tanΘ H ≈ 2 its field-driven ferromagnetic (FM)...
The authors combine angle-resolved photoemission spectroscopy, scanning tunneling microscopy, core level measurements, and theoretical calculations to demonstrate the surface charge induced Dirac band splitting in a density wave material, (TaSe${}_{4}$)${}_{2}$I.
TaAs and NbAs are two of the earliest identified Weyl semimetals that possess many intriguing optical properties, such as chirality-dependent excitations giant second harmonic generation (SHG). Linear nonlinear optics have been employed tools to probe physics in these crystals. Here we extend studies address important points: determining complete anisotropic dielectric response, explore if how they can reveal essential physics. For first time, determine functions by combining spectroscopic...
The Wiedemann-Franz (WF) law relates the electronic component of thermal conductivity to electrical in metals through Lorenz number. WF has proven be remarkably robust, however violations have been observed many topological materials. In this work, we report thermoelectric measurements conducted on Heusler, ferromagnetic, Weyl semimetal Co$_2$MnAl which shows a drastic, temperature dependent violation below 300 K. We then discuss our result context known physical explanations for violation....
Spin-valley locking in monolayer transition metal dichalcogenides has attracted enormous interest, since it offers potential for valleytronic and optoelectronic applications. Such an exotic electronic state sparsely been seen bulk materials. Here, we report spin-valley a Dirac semimetal BaMnSb2. This is revealed by comprehensive studies using first principles calculations, tight-binding effective model analyses, angle-resolved photoemission spectroscopy measurements. Moreover, this material...
The origin of the pseudogap in many strongly correlated materials has been a longstanding puzzle. Here, we present experimental evidence that many-body interactions among small Holstein polarons, i.e., formation bipolarons, are primarily responsible for (TaSe4)2I. After weak photoexcitation material, observe appearance both dispersive (single-particle bare band) and flat bands (single-polaron sub-bands) gap by using time- angle-resolved photoemission spectroscopy. Based on Monte Carlo...
Axion electrodynamics in condensed matter could emerge from the formation of charge density waves (CDWs) Weyl semimetals. (TaSe$_4$)$_2$I was proposed to be first material platform for realizing axionic CDW that may host topological defects with one-dimensional in-gap modes. The real-space modulation phase and existence modes remain elusive. Here, we present a comprehensive scanning tunneling microscopic spectroscopic study on (110) surface. measurements reveal gap $\sim 200$ meV, good...
Nonreciprocal (NR) charge transport in quantum materials has attracted enormous interest since it offers an avenue to investigate symmetry related physics and holds many prospective applications such as rectification photodetection over a wide range of frequencies. The NR reported date occurs along the longitudinal direction with resistance limited few percent ohmic resistance. Here we report transverse nonreciprocal phenomenon divergent nonreciprocity - colossal Hall effect. This is...
We report thermal conductivity and Seebeck effect measurements on $\text{Mn}{({\text{Bi}}_{1\ensuremath{-}x}{\text{Sb}}_{x})}_{2}{\text{Te}}_{4}$ (MBST) with $x=0.26$ under applied magnetic fields below $50\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. Our data shows clear indications of the electronic structure transition induced by antiferromagnetic (AFM) to ferromagnetic (FM) driven field as well significant positive magnetothermal in Weyl semimetal state MBST. Further, examining dependence...
There is tremendous interest in employing collective excitations of the lattice, spin, charge, and orbitals to tune strongly correlated electronic phenomena. We report such an effect a ruthenate, Ca3Ru2O7, where two phonons with strong electron-phonon coupling modulate pseudogap as well mediate charge spin density wave fluctuations. Combining temperature-dependent Raman spectroscopy functional theory reveals phonons, B2P B2M, that are coupled electrons whose scattering intensities...
The copper substituted lead oxyapatite, Pb$_{10-x}$Cu$_{x}$(PO$_{3.92(4)}$)$_{6}$O$_{0.96(3)}$ (x=0.94(6)) was studied using neutron and x-ray diffraction spectroscopy techniques. crystal structure of the main phase our sample, which has come to be colloquially known as LK-99, is verified possess a hexagonal with space group $P 6_{3}/m$, alongside presence impurity phases Cu Cu$_2$S. We determine primary substitution location Pb1 ($6h$) site, small at Pb2 ($4f$) site. Consequently, no clear...
There was significant discussion regarding the potential for room-temperature superconductivity in copper-substituted lead apatite which has come to be known as LK-99. Neutron diffraction and spectroscopy were employed examine this compound. We did not observe a superconducting resonance, nor we any predicted Cu-induced structural distortion between 5 300 K. No magnetic long-range order or excitations detected temperature range. have determined favored substitution site of copper at Pb1...