A5045221838- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Multiferroics and related materials
- Rare-earth and actinide compounds
- Theoretical and Computational Physics
- Iron-based superconductors research
- Crystal Structures and Properties
- Topological Materials and Phenomena
- Magnetic properties of thin films
- Inorganic Chemistry and Materials
- Nuclear Physics and Applications
- Nuclear materials and radiation effects
- Crystallization and Solubility Studies
- Magnetism in coordination complexes
- Magneto-Optical Properties and Applications
- Catalysis and Oxidation Reactions
- Algebraic structures and combinatorial models
- Transition Metal Oxide Nanomaterials
- Perovskite Materials and Applications
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- High-pressure geophysics and materials
- Quantum many-body systems
- Graphene research and applications
Georgia Institute of Technology
2016-2025
State Street (United States)
2020
London Centre for Nanotechnology
2020
University College London
2020
Massachusetts Institute of Technology
2020
Johns Hopkins University
2012-2019
École Polytechnique Fédérale de Lausanne
2010-2018
University of Baltimore
2015
Cornell University
2015
Institut Laue-Langevin
2010-2014
We elucidate the role of magnon interaction and spontaneous decays in spin dynamics triangular-lattice Heisenberg antiferromagnet by calculating its dynamical structure factor within spin-wave theory. Explicit theoretical results for neutron-scattering intensity are provided spins S=1/2 S=3/2. The exhibits unconventional features such as quasiparticle peaks broadened decays, non-Lorentzian lineshapes, significant spectral weight redistribution to two-magnon continuum. This rich excitation...
Magnetization plateaus in quantum magnets---where bosonic quasiparticles crystallize into emergent spin superlattices---are spectacular yet simple examples of collective phenomena escaping classical description. While magnetization have been observed a number spin-1/2 antiferromagnets, the description their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate dynamical properties triangular-lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$ its one-third...
Lanthanides in the trivalent oxidation state are typically described using an ionic picture that leads to localized magnetic moments. The hierarchical energy scales associated with lanthanides produce desirable properties for e.g., molecular magnetism, quantum materials, and transduction. Here, we show this traditional paradigm breaks down praseodymium tetravalent state. Synthetic, spectroscopic, theoretical tools deployed on several solid-state Pr
Simulating quantum spin systems at finite temperatures is an open challenge in many-body physics. This work studies the temperature-dependent dynamics of a pivotal compound, ${\mathrm{FeI}}_{2}$, to determine if universal effects can be accounted for by phenomenological renormalization dynamical structure factor $S(\mathbf{q},\ensuremath{\omega})$ measured inelastic neutron scattering. Renormalization schemes based on quantum-to-classical correspondence principle are commonly applied low...
Polarized and unpolarized neutron scattering experiments on the frustrated ferromagnetic spin-$1/2$ chain ${\mathrm{LiCuVO}}_{4}$ show that phase transition at ${H}_{\mathrm{Q}}$ of 8 T is driven by quadrupolar fluctuations dipolar correlations are short range with moments parallel to applied magnetic field in high-field phase. Heat-capacity measurements evidence a into this phase, an anomaly clearly different from low fields. Our experimental data consistent picture where ground state above...
A quantum magnet, ${\mathrm{LiCuSbO}}_{4}$, with chains of edge-sharing spin-$\frac{1}{2}$ ${\mathrm{CuO}}_{6}$ octahedra is reported. While short-range order observed for $T<10\text{ }\text{ }\mathrm{K}$, no zero-field phase transition or spin freezing occurs down to 100 mK. Specific heat indicates a distinct high-field near the 12 T saturation field. Neutron scattering shows incommensurate correlations $q=(0.47\ifmmode\pm\else\textpm\fi{}0.01)\ensuremath{\pi}/a$ and places an upper limit...
Abstract The Ising model—in which degrees of freedom (spins) are binary valued (up/down)—is a cornerstone statistical physics that shows rich behaviour when spins occupy highly frustrated lattice such as kagome. Here we show the layered magnet Dy 3 Mg 2 Sb O 14 hosts an emergent order predicted theoretically for individual kagome layers in-plane spins. Neutron-scattering and bulk thermomagnetic measurements reveal phase transition at ∼0.3 K from disordered spin-ice-like regime to charge...
Inelastic neutron scattering at low temperatures $T\ensuremath{\le}30\text{ }\text{ }\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}\phantom{\rule{0ex}{0ex}}K$ from a powder of ${\mathrm{LiZn}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ demonstrates this triangular-lattice antiferromagnet hosts collective magnetic excitations spin-$1/2$ ${\mathrm{Mo}}_{3}{\mathrm{O}}_{13}$ molecules. Apparently gapless ($\mathrm{\ensuremath{\Delta}}<0.2\text{ }\mathrm{meV}$) and extending least up to 2.5 meV,...
One-dimensional (1D) magnetic insulators have attracted significant interest as a platform for studying emergent phenomena such quasiparticle fractionalization and quantum criticality. The antiferromagnetic Heisenberg chain of spins-1/2 is an important reference system; its elementary excitations are spin-1/2 quasiparticles called spinons that always created in pairs. However, while inelastic neutron scattering (INS) experiments routinely observe the excitation continuum associated with...
The spin-1/2 triangular lattice antiferromagnet YbMgGaO$_{4}$ has attracted recent attention as a quantum spin-liquid candidate with the possible presence of off-diagonal anisotropic exchange interactions induced by spin-orbit coupling. Whether is stabilized or not depends on interplay various chemical disorder that inherent to layered structure compound. We combine time-domain terahertz spectroscopy and inelastic neutron scattering measurements in field polarized state obtain better...
Iron pnictides and selenides display a variety of unusual magnetic phases originating from the interplay between electronic, orbital, lattice degrees freedom. Using powder inelastic neutron scattering on two-leg ladder BaFe2Se3, we fully characterize static dynamic spin correlations associated with Fe4 block state, an exotic ground state observed in this low-dimensional magnet Rb0.89Fe1.58Se2. All excitations predicted by effective Heisenberg model localized spins are below 300 meV...
The perovskite ${\mathrm{Ba}}_{8}{\mathrm{CoNb}}_{6}{\mathrm{O}}_{24}$ comprises equilateral effective spin-$\frac{1}{2} {\mathrm{Co}}^{2+}$ triangular layers separated by six nonmagnetic layers. Susceptibility, specific heat, and neutron scattering measurements combined with high-temperature series expansions spin-wave calculations confirm that is basically a two-dimensional magnet no detectable spin anisotropy long-range magnetic ordering down to 0.06 K. In other words, very close be...
We report a comprehensive inelastic neutron-scattering study of the frustrated pyrochlore antiferromagnet MgCr2O4 in its cooperative paramagnetic regime. Theoretical modeling yields microscopic Heisenberg model with exchange interactions up to third-nearest neighbors, which quantitatively explains all details dynamic magnetic response. Our work demonstrates that excitations are faithfully represented entire Brillouin zone by theory magnons propagating highly-correlated background. results...
Three-dimensionally (3D) frustrated magnets generally exist in the magnetic diamond and pyrochlore lattices, which quantum fluctuations suppress orders generate highly entangled ground states. LiYbSe2 a previously unreported lattice was discovered from LiCl flux growth. Distinct spin liquid (QSL) candidate NaYbSe2 hosting perfect triangular of Yb3+, crystallizes cubic structure with space group Fd3m (No. 227). The Yb3+ ions are arranged on network corner-sharing tetrahedra, is particularly...
Crystal field (CF) control of rare-earth (RE) ions has been employed to minimize decoherence in qubits and enhance the effective barrier single-molecule magnets. The CF approach focused on effects symmetry dynamic magnetic properties. Herein, magnitude is increased via RE oxidation state. enhanced 4f metal-ligand covalency Pr
Using low-energy projection of the one-band t-t'-t"-Hubbard model we derive an effective spin-Hamiltonian and its spin-wave expansion to order 1/S. We fit dispersion several parent compounds high-temperature superconducting cuprates: La2CuO4, Sr2CuO2Cl2 Bi2Sr2YCu2O8. Our accurate quantitative determination Hubbard parameters allows prediction comparison experimental results measurable quantities such as staggered moment, double occupancy density, velocity bimagnon excitation spectrum density...
For materials near the phase boundary between weak and strong topological insulators (TIs), their band topology depends on alignment, with inverted (normal) corresponding to (weak) TI phase. Here, taking anisotropic transition-metal pentatelluride ${\mathrm{ZrTe}}_{5}$ as an example, we show that inversion manifests itself a second extremum (band gap) in layer stacking direction, which can be probed experimentally via magnetoinfrared spectroscopy. Specifically, find anisotropy of features...
A ferroelectric field-effect transistor (FeFET) with scaled dimensions (170 nm and 24 of gate width length, respectively) a 10 thick Si doped HfO2 in the oxide stack are characterized at cryogenic temperatures down to 6.9 K. We observe that decrease temperature leads an increase memory window expense increased program/erase voltage. This is consistent coercive field due suppression thermally activated domain wall creep motion temperatures. However, observed insensitivity location respect...