A5054475705- Advanced Condensed Matter Physics
- Iron-based superconductors research
- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- 2D Materials and Applications
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Inorganic Chemistry and Materials
- Magnetic and transport properties of perovskites and related materials
- Advanced Chemical Physics Studies
- Phase-change materials and chalcogenides
- Organic and Molecular Conductors Research
- High-pressure geophysics and materials
- Ferroelectric and Piezoelectric Materials
- Graphene research and applications
- Magnetic properties of thin films
- Fullerene Chemistry and Applications
- Amyloidosis: Diagnosis, Treatment, Outcomes
- Crystal Structures and Properties
- Metalloenzymes and iron-sulfur proteins
- Nanocluster Synthesis and Applications
- Perovskite Materials and Applications
- Inorganic Fluorides and Related Compounds
- Organoselenium and organotellurium chemistry
- Machine Learning in Materials Science
Rice University
2020-2024
University of Virginia
2015-2020
The geometrical frustration nature of the kagome lattice makes it a great host to flat electronic band, non-trivial topological properties, and novel magnetisms. Metallic antiferromagnet YMn$_{6}$Sn$_{6}$ exhibits Hall effect (THE) when an in-plane magnetic field is applied. THE typically associated with nanometer-sized non-coplanar spin structure skyrmions in non-centrosymmetric magnets large Dzyaloshinskii-Moriya interaction. Here we use single crystal neutron diffraction determine...
Triangular lattice of rare-earth ions with interacting effective spin-1/2 local moments is an ideal platform to explore the physics quantum spin liquids (QSLs) in presence strong spin-orbit coupling, crystal electric fields, and geometrical frustration. The Yb delafossites, NaYbCh2 (Ch=O, S, Se) forming a perfect triangular lattice, have been suggested be candidates for QSLs. Previous thermodynamics, nuclear magnetic resonance, powder-sample neutron scattering measurements on supported...
We use neutron scattering to show that ferromagnetic (FM) phase transition in the two-dimensional (2D) honeycomb lattice ${\mathrm{CrI}}_{3}$ is a weakly first order and controlled by spin-orbit coupling (SOC) induced magnetic anisotropy, instead of exchange as conventional ferromagnet. With increasing temperature, magnitude seen spin gap at Brillouin zone center, decreases power law fashion vanishes ${T}_{C}$, while in-plane $c$-axis spin-wave stiffnesses associated with couplings remain...
Spin-triplet superconductors are of extensive current interest because they can host topological state and Majorana fermions important for quantum computation. The uranium-based heavy-fermion superconductor ${\mathrm{UTe}}_{2}$ has been argued as a spin-triplet similar to ${\mathrm{UGe}}_{2}$, URhGe, UCoGe, where the superconducting phase is near (or coexists with) ferromagnetic (FM) instability electron pairing driven by FM spin fluctuations. Here we use neutron scattering show that,...
Spontaneous symmetry breaking—the phenomenon in which an infinitesimal perturbation can cause the system to break underlying symmetry—is a cornerstone concept understanding of interacting solid-state systems. In typical series temperature-driven phase transitions, higher-temperature phases are more symmetric due stabilizing effect entropy that becomes dominant as temperature is increased. However, opposite rare but possible when there multiple degrees freedom system. Here, we present such...
Quantum spin liquid (QSL) is a disordered state of quantum-mechanically entangled spins commonly arising from frustrated magnetic dipolar interactions. However, QSL in some pyrochlore magnets can also come octupolar Although the key signature for both and interaction-driven presence excitation continuum (spinons) quantum number fractionalization, an external field-induced ferromagnetic order will transform spinons into conventional waves QSL. By contrast, octupole QSL, carry moments that do...
Magnetic order in most materials occurs when magnetic ions with finite moments arrange a particular pattern below the ordering temperature. Intriguingly, if crystal electric field (CEF) effect results spin-singlet ground state, can still occur due to exchange interactions between neighboring admixing excited CEF levels. The excitations such state are spin excitons generally dispersionless reciprocal space. Here we use neutron scattering study stoichiometric Ni2Mo3O8, where Ni2+ form...
Abstract Triangular lattice of rare-earth ions with interacting effective spin-1/2 local moments is an ideal platform to explore the physics quantum spin liquids (QSLs) in presence strong spin-orbit coupling, crystal electric fields, and geometrical frustration. The Yb delafossites, NaYb Ch 2 ( =O, S, Se) forming a perfect triangular lattice, have been suggested be candidates for QSLs. Previous thermodynamics, nuclear magnetic resonance, powder sample neutron scattering measurements on...
Abstract Topological superconductors (TSC) can host exotic quasiparticles such as Majorana fermions, poised the fundamental qubits for quantum computers. TSC’s are predicted to form a superconducting gap in bulk, and gapless surface/edges states which lead emergence of zero energy modes. A candidate TSC is layered dichalcogenide MoTe 2 , type-II Weyl (semi)metal non-centrosymmetric orthorhombic (T d ) phase. It becomes upon cooling below 0.25 K, while under pressure, superconductivity...
Using elastic neutron scattering on single crystals of MoTe$_{2}$ and Mo$_{1-x}$W$_{x}$Te$_{2}$ ($x \lesssim 0.01$), the temperature dependence recently discovered T$_{d}^{*}$ phase, present between low orthorhombic T$_{d}$ phase high monoclinic 1T$^{\prime}$ is explored. The appears only warming from observed in hysteresis region prior to transition. This consists four layers its unit cell, constructed by an "AABB" sequence layer stacking operations rather than "AB" "AA" sequences phases,...
Electronic tunability in crystals with weakly bound layers can be achieved through layer stacking order. One such example is ${\mathrm{MoTe}}_{2}$, where the low-temperature orthorhombic ${T}_{d}$ phase topological and host to Weyl quasiparticles. The transition mechanism nontrivial topology elucidated by single-crystal neutron diffraction. Upon cooling from monoclinic $1{T}^{\ensuremath{'}}$ phase, diffuse scattering accompanies transition, arising random, in-plane displacements, dissipates...
The composition dependence of the structural transition between monoclinic $1{T}^{\ensuremath{'}}$ and orthorhombic ${T}_{d}$ phases in ${\mathrm{Mo}}_{1\ensuremath{-}x}{\mathrm{W}}_{x}{\mathrm{Te}}_{2}$ Weyl semimetal was investigated by elastic neutron scattering on single crystals up to $x\ensuremath{\approx}0.54$. First observed ${\mathrm{MoTe}}_{2}$, from is accompanied an intermediate pseudo-orthorhombic phase, ${T}_{d}^{*}$. Upon doping with W, ${T}_{d}^{*}$ phase vanishes...
The role of phase separation and the effect Fe-vacancy ordering in emergence superconductivity alkali metal doped iron selenides ${\mathrm{A}}_{x}{\mathrm{Fe}}_{2\ensuremath{-}y}{\mathrm{Se}}_{2}$ (A = K, Rb, Cs) is explored. High energy x-ray diffraction Monte Carlo simulation were used to investigate crystal structure quenched superconducting (SC) as-grown nonsuperconducting (NSC) ${\mathrm{K}}_{x}{\mathrm{Fe}}_{2\ensuremath{-}y}{\mathrm{Se}}_{2}$ single crystals. coexistence superlattice...
The ferroelectric phase transition in RMnO3 breaks both Z3 and Z2 symmetries, giving rise to 6 structural domains. Topological protected vortices are formed at the junctions of all domains, is closely related these Z6 vortices. In this work, Monte-Carlo studies on magnetic have been performed system. simulation results lattices with different domain distributions induced by external electric field simulated quenching show temperature T s , indicating that coupling magnetism ferroelectricity...
Magnetic order in most materials occurs when magnetic ions with finite moments a crystalline lattice arrange particular pattern below the ordering temperature determined by exchange interactions between ions. However, crystal electric field (CEF) effect results spin-singlet ground state on individual sites, collective of system can either remain non-magnetic, or more intriguingly, neighboring ions, provided they are sufficiently strong, admix excited CEF levels, resulting magnetically...
Spontaneous symmetry breaking-the phenomenon where an infinitesimal perturbation can cause the system to break underlying symmetry-is a cornerstone concept in understanding of interacting solid-state systems. In typical series temperature-driven phase transitions, higher temperature phases are more symmetric due stabilizing effect entropy that becomes dominant as is increased. However, opposite rare but possible when there multiple degrees freedom system. Here, we present such example...