A5030940556- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Topological Materials and Phenomena
- Multiferroics and related materials
- Inorganic Chemistry and Materials
- Crystal Structures and Properties
- Graphene research and applications
- Magnetic Properties of Alloys
- Nuclear materials and radiation effects
Johns Hopkins University
2022-2025
McMaster University
2019-2020
${\mathrm{Eu}}_{5}{\mathrm{In}}_{2}{\mathrm{Sb}}_{6}$ is an orthorhombic nonsymmorphic small band gap semiconductor with three distinct ${\mathrm{Eu}}^{2+}$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances known stoichiometric antiferromagnets belongs to a family Zintl materials that may host axion insulator. Using single crystal neutron diffraction, we show...
Zintl phases, containing strongly covalently bonded frameworks with separate ionically ions, have emerged as a critical materials family in which to couple magnetism and strong spin-orbit coupling drive diverse topological phases of matter. Here we report the single-crystal synthesis, magnetic, thermodynamic, transport, theoretical properties compound EuZn2P2 that crystallizes anti-La2O3 P-3m1 structure, triangular layers Eu2+ ions. In-plane resistivity measurements reveal insulating...
Dirac material LaCuSb 2 shows anisotropic superconducting response to applied magnetic fields.
Among the pyrochlore oxides, frustrated magnet Tb2Ti2O7 has drawn intense interest as a spin liquid candidate. Its unusual magnetic properties rely on careful balance of interactions lattice and are exquisitely sensitive to composition. Leveraging precise stoichiometry control reactive-oxide molecular beam epitaxy, we manipulate defect chemistry thin films (111)-oriented YSZ substrates probe their structural properties. Single-phase realized within large growth window at up 25%...
The tetragonal heavy-fermion superconductor CeRh2As2 (Tc=0.3 K) exhibits an exceptionally high critical field of 14 T for B∥c. It undergoes a field-driven first-order phase transition between superconducting states, potentially transitioning from spin-singlet to spin-triplet superconductivity. To further understand these states and the role magnetism, we probe spin fluctuations in using neutron scattering. We find dynamic (π,π) antiferromagnetic (AFM) correlations with anisotropic...
Frustrated magnets provide an exciting playground for the study of exotic magnetic properties. Here, authors use a combination neutron scattering and muon spin rotation to determine crystal electric fields, anisotropy, structure Er${}_{3}$Ga${}_{5}$O${}_{12}$, as well fingerprints dynamical ground state. These findings shows excellent model system studying complexities metamagnetism.
We present a detailed magnetic study of the triangular antiferromagnet ${\mathrm{ErMgGaO}}_{4}$. A point charge calculation under single ion approximation reveals crystal field ground state doublet with strong Ising-like behavior ${\mathrm{Er}}^{3+}$ moment along $c$ axis. Magnetic susceptibility and specific heat measurements indicate no presence transitions above 0.1 K evidence residual entropy as temperature approaches zero. Zero (ZF) $\ensuremath{\mu}\mathrm{SR}$ shows sign static...
Planar tunneling spectroscopy of the Kondo insulator SmB$_6$ suggests that an interaction between surface Dirac fermions and bulk spin excitons results in incompletely protected topological states. To gain further insight into their true nature, it is necessary to study other candidates. Calculations electronic energy bands predict YbB$_{12}$ hosts states by crystalline mirror symmetry. In this study, we present conductance spectra obtained from (001) single crystals discuss them comparison...
${\mathrm{BaCo}}_{2}({\mathrm{AsO}}_{4}){}_{2}$ (BCAO) has seen extensive study since its initial identification as a proximate Kitaev quantum spin liquid candidate. Thought to be described by the highly anisotropic XXZ-${J}_{1}\text{\ensuremath{-}}{J}_{3}$ model, ease with which magnetic order is suppressed in system indicates proximity phase. Upon chemical tuning via partial arsenic substitution vanadium, we show an suppression of long-range incommensurate BCAO $T\ensuremath{\approx}3.0$...
The tetragonal heavy-fermion superconductor CeRh$_2$As$_2$ ($T_{\rm c}=0.3$ K) exhibits an exceptionally high critical field of 14 T for $\textbf{B} \parallel \textbf{c}$. It undergoes a field-driven first-order phase transition between superconducting (SC) states, potentially transitioning from spin-singlet to spin-triplet superconductivity. To elucidate the underlying pairing mechanism, we probe spin fluctuations in using neutron scattering. We find dynamic $(\pi,\pi)$ antiferromagnetic...
Weyl fermions can arise from time-reversal symmetry-breaking magnetism, but their impact on magnetic order is a source of ongoing research. Using high-precision neutron diffraction and spectroscopy, we present comprehensive exploration the structure excitation spectrum semimetal helical magnet NdAlSi. We use Luttinger-Tisza, classical mean-field, random-phase approximation techniques to model dispersive crystal field excitons. find extended-ranged sign-changing interactions, suggesting...
Studying superconductivity in Dirac semimetals is an important step understanding quantum matter with topologically non-trivial order parameters. We report on the properties of superconducting phase single crystals material LaCuSb2 prepared by self-flux method. find that chemical and hydrostatic pressure drastically suppress transition. Furthermore, due to large Fermi surface anisotropy, magnetization muon spin relaxation measurements reveal Type-II for applied magnetic fields along...
Eu$_5$In$_2$Sb$_6$ is an orthorhombic non-symmorphic small band gap semiconductor with three distinct Eu$^{2+}$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances known stoichiometric antiferromagnets belongs to a family Zintl materials that may host axion insulator. Using single crystal neutron diffraction, we show $T_{\mathrm{N1}}=14\mathrm{~K}$ second-order transition associated long-range antiferromagnetic...
Zintl phases, containing strongly covalently bonded frameworks with separate ionically ions, have emerged as a critical materials family in which to couple magnetism and strong spin-orbit coupling drive diverse topological phases of matter. Here we report the single-crystal synthesis, magnetic, thermodynamic, transport, theoretical properties compound EuZn2P2 that crystallizes anti-La2O3 P-3m1 structure, triangular layers Eu2+ ions. In-plane resistivity measurements reveal insulating...
BaCo2(AsO4)2 (BCAO) has seen extensive study since its initial identification as a proximate Kitaev quantum spin liquid candidate. Thought to be described by the highly anisotropic XXZ-J_1-J_3 model, ease with which magnetic order is suppressed in system indicates proximity phase. Upon chemical tuning via partial arsenic substitution vanadium, we show an suppression of long-range incommensurate BCAO T = 3.0 K, followed increased freezing at higher levels. Between these two regions, around...