A5083882798- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Advanced Condensed Matter Physics
- Organic and Molecular Conductors Research
- Graphene research and applications
- Magnetism in coordination complexes
- Magnetic and transport properties of perovskites and related materials
- 2D Materials and Applications
- Quantum and electron transport phenomena
- Quantum, superfluid, helium dynamics
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
- Crystallization and Solubility Studies
- High-pressure geophysics and materials
- Inorganic Chemistry and Materials
- Magnetic Properties of Alloys
- X-ray Diffraction in Crystallography
- Cold Atom Physics and Bose-Einstein Condensates
- Magnetic properties of thin films
- N-Heterocyclic Carbenes in Organic and Inorganic Chemistry
- Advanced Thermoelectric Materials and Devices
- Diamond and Carbon-based Materials Research
- Advanced Chemical Physics Studies
Florida State University
2016-2025
National High Magnetic Field Laboratory
2016-2025
Knoxville College
2023
University of Tennessee at Knoxville
2023
Oak Ridge National Laboratory
2023
Tallahassee Orthopedic Clinic
2019
Institute of Photonic Sciences
2019
University of California, Berkeley
2019
National Institute for Materials Science
2004-2018
University of Tsukuba
2018
We present Raman spectroscopy measurements on single- and few-layer graphene flakes. Using a scanning confocal approach we collect spectral data with spatial resolution, which allows us to directly compare images force micrographs. Single-layer can be distinguished from double- by the width of D' line: single peak for single-layer splits into different peaks double-layer. These findings are explained using double-resonant model based ab-initio calculations electronic structure phonon...
Upping the pressure in bilayer graphene The discovery of superconductivity and exotic insulating phases twisted has established this material as a model system strongly correlated electrons. To achieve superconductivity, two layers need to be at very precise angle with respect each other. Yankowitz et al. now show that another experimental knob, hydrostatic pressure, can used tune phase diagram (see Perspective by Feldman). Applying increased coupling between layers, which shifted...
A Dirac nodal-line semimetal phase, which represents a new quantum state of topological materials, has been experimentally realized only in few systems, including PbTaSe2, PtSn4, and ZrSiS. In this Letter, we report evidence fermions ZrSiSe ZrSiTe probed de Haas–van Alphen oscillations. Although share similar layered structure with ZrSiS, our studies show the Fermi surface (FS) enclosing nodal line 2D character ZrSiTe, contrast 3D-like FS Another important property revealed experiment is...
$\mathrm{MnBi_2Te_4}$ has recently been established as an intrinsic antiferromagnetic (AFM) topological insulator and predicted to be ideal platform realize quantum anomalous Hall (QAH) axion states. We performed comprehensive studies on the structure, nontrivial surface state magnetotransport properties of this material. Our results reveal effect arising from a non-collinear spin structure for magnetic field parallel $c$-axis. also observed remarkable negative magnetoresistance under...
In the quest to increase critical temperature Tc of cuprate superconductors, it is essential identify factors that limit strength superconductivity. The upper field Hc2 a fundamental measure strength, yet there no agreement on its magnitude and doping dependence in superconductors. Here we show thermal conductivity can be used directly detect cuprates YBa2Cu3Oy, YBa2Cu4O8 Tl2Ba2CuO6+δ, allowing us map out across phase diagram. It exhibits two peaks, each located at point where Fermi surface...
We report on the unusual behavior of in-plane thermal conductivity ($\kappa$) and torque ($\tau$) response in Kitaev-Heisenberg material $\alpha$-RuCl$_3$. $\kappa$ shows a striking enhancement with linear growth beyond H = 7 T, where magnetic order disappears, while $\tau$ for both symmetry directions an anomaly at same field. The temperature- field-dependence are far more complex than conventional phonon magnon contributions, require us to invoke presence unconventional spin excitations...
We report on Coulomb blockade and diamond measurements an etched, tunable single-layer graphene quantum dot. The device consisting of a island connected via two narrow constrictions is fully by three lateral gates. resonances are observed from measurements, charging energy ≈3.5meV extracted. For increasing temperatures, we detect peak broadening transmission increase the nanostructured barriers.
We present spatially resolved Raman images of the G and 2D lines single-layer graphene flakes. The spatial fluctuations are correlated thus shown to be affiliated with local doping domains. investigate position line—the most significant peak identify graphene—as a function charging up ∣n∣≈4×1012cm−2. Contrary line which exhibits strong symmetric stiffening respect electron hole doping, shows weak slightly asymmetric for low doping. Additionally, linewidth is, in contrast line, independent...
The extremely large transverse magnetoreistance (the magnetoresistant ratio $\sim 1.3\times10^5\%$ in 2 K and 9 T field, $4.3\times 10^6\%$ 0.4 32 without saturation), the metal-semiconductor crossover induced by magnetic are reported NbSb$_2$ single crystal with electric current parallel to $b$-axis. is preserved when along $ac$-plane but significantly suppressed. sign reversal of Hall resistivity field close point, electronic structure calculation reveals coexistence a small number holes...
We report two-dimensional quantum transport in SrMnBi$_2$ single crystals. The linear energy dispersion leads to the unusual nonsaturated magnetoresistance since all Dirac fermions occupy lowest Landau level limit. transverse exhibits a crossover at critical field $B^*$ from semiclassical weak-field $B^2$ dependence high-field linear-field dependence. With increase temperature, increases and temperature of satisfies quadratic behavior which is attributed splitting dispersion. effective...
Abstract The recent breakthrough in the discovery of Weyl fermions monopnictide semimetals provides opportunities to explore exotic properties relativistic condensed matter. chiral anomaly-induced negative magnetoresistance and π Berry phase are two fundamental transport associated with topological characteristics semimetals. Since multiple-band systems, resolving clear for each Fermi pocket remains a challenge. Here we report determination phases multiple pockets semimetal TaP through high...
We report two-dimensional Dirac fermions and quantum magnetoresistance in single crystals of CaMnBi${}_{2}$. The nonzero Berry's phase, small cyclotron resonant mass, first-principles band structure suggest the existence Bi square nets. in-plane transverse exhibits a crossover at critical field ${B}^{*}$ from semiclassical weak-field ${B}^{2}$ dependence to high-field unsaturated linear ($\ensuremath{\sim}$$120%$ 9 T 2 K) due limit fermions. temperature satisfies quadratic behavior, which is...
The connection of novel electromagnetic responses to Weyl nodes in topological semimetals is intriguing but difficult establish experiments. Here, the authors discover CeAlSi be a new ferromagnetic semimetal by combining first-principles calculations with various experimental techniques. These reveal loop Hall effect that induced purely proximity material's Fermi level its nodes. can potentially result from arcs located on magnetic domain walls.
Abstract The 2-dimensional layered oxide material SrCu 2 (BO 3 ) , long studied as a realization of the Shastry-Sutherland spin topology, exhibits range intriguing physics function both hydrostatic pressure and magnetic field, with still debated intermediate plaquette phase appearing at approximately 20 kbar possible deconfined critical point higher pressure. Here, we employ tunnel diode oscillator (TDO) technique to probe behavior in combined extreme conditions high pressure, low...
Abstract The kagome lattice has long been regarded as a theoretical framework that connects geometry to unusual singularities in electronic structure. Transition metal compounds have recently identified promising material platform investigate the long-sought flat band. Here we report signature of two-dimensional band at surface antiferromagnetic FeSn by means planar tunneling spectroscopy. Employing Schottky heterointerface and an n-type semiconductor Nb-doped SrTiO 3 , observe anomalous...
We have investigated the normal state Fermi-surface properties of kagome superconductor ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ using torque magnetometry with applied fields ($H$) up to 35 T. The signal shows clear de Haas--van Alphen (dHvA) oscillations above 15 are smooth and consist seven distinct frequencies values from $\ensuremath{\sim}$ 18 T 2135 presence higher in is further confirmed by carrying out additional measurements tunnel diode oscillator technique. All measured at different...