A5011198296- Rare-earth and actinide compounds
- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Magnetic Properties of Alloys
- Inorganic Chemistry and Materials
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Nuclear Materials and Properties
- Topological Materials and Phenomena
- High-pressure geophysics and materials
- Thermodynamic and Structural Properties of Metals and Alloys
- Advanced Chemical Physics Studies
- Superconductivity in MgB2 and Alloys
- X-ray Diffraction in Crystallography
- Superconducting Materials and Applications
- Advanced Materials Characterization Techniques
- Metallurgical and Alloy Processes
- Radioactive element chemistry and processing
- Crystallization and Solubility Studies
- Quantum and electron transport phenomena
- Magnetic properties of thin films
- Intellectual Capital and Performance Analysis
- Nuclear physics research studies
- Solid-state spectroscopy and crystallography
- Graphene research and applications
Los Alamos National Laboratory
2016-2025
Government of the United States of America
2023
Hunter Douglas (United States)
2022
Scottish Universities Physics Alliance
2022
University of St Andrews
2022
Max Planck Institute for Chemical Physics of Solids
2022
Florida State University
2019
The University of Texas at Austin
2018
Japan Atomic Energy Agency
2011-2016
Advanced Science Research Center
2011-2016
Superconductivity has been observed in ${\mathrm{PrOs}}_{4}{\mathrm{Sb}}_{12}$ at ${T}_{C}=1.85 \mathrm{K}$ and appears to involve heavy fermion quasiparticles with an effective mass ${m}^{*}\ensuremath{\sim}50 {m}_{e}$ as inferred from the jump specific heat ${T}_{C},$ upper critical field near normal state electronic heat. Thermodynamic transport measurements suggest that a quadrupolar origin, although magnetic origin cannot be completely ruled out.
Strong magnetic fluctuations can provide a coupling mechanism for electrons that leads to unconventional superconductivity. Magnetic order and superconductivity have been found coexist in number of magnetically mediated superconductors, but these parameters generally compete. We report close the upper critical field, CeCoIn 5 adopts multicomponent ground state simultaneously carries cooperating superconducting orders. Suppressing first-order transition at field simultaneous collapse order,...
UTe2 is a newly-discovered unconventional superconductor wherein multicomponent topological superconductivity anticipated based on the presence of two superconducting transitions and time-reversal symmetry breaking in state. The observation transitions, however, remains controversial. Here we demonstrate that single crystals displaying an optimal transition temperature at 2 K exhibit remarkably high quality supported by their small residual heat capacity state large resistance ratio. Our...
We have carried out ${}^{115}\mathrm{In}$ and ${}^{59}\mathrm{Co}$ nuclear quadrupole resonance magnetic measurements on ${\mathrm{CeCoIn}}_{5}$ ${\mathrm{CeIrIn}}_{5}.$ The temperature T dependence of the spin-lattice relaxation rate ${1/T}_{1}$ in normal state indicates that is located just at an antiferromagnetic instability, ${\mathrm{CeIrIn}}_{5}$ nearly region. In superconducting state, has no Hebel-Slichter coherence peak below ${T}_{C}$ a power-law (close to ${T}^{3})$ very low...
We report pressure-induced superconductivity in a single crystal of CaFe2As2. At atmospheric pressure, this material is antiferromagnetic below 170 K but under an applied pressure 0.69 GPa becomes superconducting, with transition temperature Tc exceeding 10 K. The rate suppression magnetic field −0.7 T−1, giving extrapolated zero-temperature upper critical 10–14 T.
The filled skutterudite compound PrOs 4 Sb 12 exhibits superconductivity, with a superconducting critical temperature T c ≈1.85 K, that appears to involve heavy fermion quasiparticles an effective mass m * ≈10 2 e , where is the free electron mass. Evidence for state in based on electrical resistivity, specific heat, and magnetic susceptibility measurements normal states, reviewed. New are presented reveal decreases linearly pressure ∼20 kbar, resistivity decreasing below ∼1-2 K as power law...
We report the synthesis and basic physical properties of single crystals CaFe2As2, a compound isostructural to BaFe2As2 which has been recently doped produce superconductivity. CaFe2As2 crystallizes in ThCr2Si2 structure with lattice parameters = 3.887(4) Å c 11.758(23) Å. Magnetic susceptibility, resistivity, heat capacity all show first order phase transition at T0 171 K. The magnetic susceptibility is nearly isotropic from 2 350 data gives Sommerfeld coefficient 8.2 ± 0.3 mJ mol−1 K−2,...
We report the synthesis and physical properties of single crystals stoichiometric BaNi2As2 that crystalizes in ThCr2Si2 structure with lattice parameters a = 4.112(4) Åand c 11.54(2) Å. Resistivity heat capacity show first order phase transition at T_0 130 K thermal hysteresis 7 K. The Hall coefficient is weakly temperature dependent from room to 2 where it has value -4x10^{-10} Ω-cm/Oe. Resistivity, ac-susceptibility, find evidence for bulk superconductivity T_c 0.7 Sommerfeld 11.6 \pm 0.9...
We report transport measurement in zero and applied magnetic field on a single crystal of NbAs. Transverse longitudinal magnetoresistance the plane this tetragonal structure does not saturate up to 9 T. In transverse configuration ($H \parallel c$, $I \perp c$) it is 230,000 \% at 2 K. The Hall coefficient changes sign from hole-like room temperature electron-like below $\sim$ 150 electron carrier density mobility calculated K based band approximation are 1.8 x 10$^{19}$ cm$^{-3}$ 3.5...
Motivated by the search for design principles of rare-earth-free strong magnets, we present a study electronic structure and magnetic properties ferromagnetic metal Fe3GeTe2 within local density approximation (LDA) functional theory, its combination with dynamical mean-field theory (DMFT). For comparison to these calculations, have measured thermodynamic as well X-ray circular dichroism photoemission spectrum single crystal Fe3GeTe2. We find that experimentally determined Sommerfeld...
Magnetic force microscopy was used to observe the magnetic microstructure of Fe3GeTe2 at 4 K on (001) surface. The surface structure consists a two-phase domain branching pattern that is characteristic for highly uniaxial magnets in plane perpendicular easy axis. average width Ds = 1.3 μm determined from this pattern, combination with intrinsic properties calculated bulk magnetization data (the saturation Ms 376 emu/cm3 and magnetocrystalline anisotropy constant Ku 1.46 × 107 erg/cm3),...
Recent experimental and theoretical interest in the superconducting phase of heavy-fermion material ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$ has led to a number proposals which order parameter breaks time-reversal symmetry (TRS). In this study we measure polar Kerr effect (PKE) as function temperature for several high-quality single crystals ${\mathrm{URu}}_{2}{\mathrm{Si}}_{2}$. We find an onset PKE below transition that is consistent with TRS-breaking parameter. This appears be independent...
Uncovering the symmetry of a hidden order Cooling matter generally makes it more ordered and may induce dramatic transitions: Think water becoming ice. With increased comes loss symmetry; in its liquid form will look same however you rotate it, whereas ice not. Kung et al. studied properties mysteriously phase material URu 2 Si that appears at 17.5 K. They shone laser light on crystal shifts frequency light. The electron orbitals uranium had handedness to them alternated between atomic...
A central issue in material science is to obtain understanding of the electronic correlations that control complex materials. Such frequently arise because competition localized and itinerant degrees freedom. Although respective limits well-localized or entirely ground states are well understood, intermediate regime controls functional properties materials continues challenge theoretical understanding. We have used neutron spectroscopy investigate plutonium, which a prototypical at brink...
By introducing a superconducting gap in Weyl or Dirac semimetals, the state inherits nontrivial topology of their electronic structure. As result, superconductors are expected to host exotic phenomena, such as nonzero-momentum pairing due chiral node structure, zero-energy Majorana modes at surface. These fundamental interest improve our understanding correlated topological systems, and, moreover, practical applications phase-coherent devices and quantum have been proposed. Proximity-induced...
Thermodynamic and transport properties are reported on single crystals of the hexagonal antiferromagnet Mn3Sn grown by Sn flux technique. Magnetization measurements reveal two magnetic phase transitions at T1 = 275 K T2 200 K, below antiferromagnetic transition TN ≈ 420 K. The Hall conductivity in zero field is suppressed dramatically from 4.7 Ω−1 cm−1 to near T1, coincident with vanishing weak ferromagnetic moment. This illustrates that large anomalous effect arising Berry curvature can be...
Abstract The change in resistance of a material magnetic field reflects its electronic state. In metals with weakly- or non-interacting electrons, the typically increases upon application field. contrast, negative magnetoresistance may appear under some circumstances, e.g. , anisotropic Fermi surfaces spin-disorder scattering and semimetals Dirac Weyl structures. Here we show that non-magnetic semimetal TaAs 2 possesses very large magnetoresistance, an unknown mechanism. Density functional...
Significance <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mtext>Sr</mml:mtext> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> <mml:mtext>RuO</mml:mtext> <mml:mn>4</mml:mn> </mml:math> is distinctive among unconventional superconductors, in that addition to exhibiting evidence for strong correlations, it stoichiometric and extremely clean. As a result, its electronic structure unusually well characterized, rendering an ideal platform...