A5062545279- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Multiferroics and related materials
- Nuclear materials and radiation effects
- Magnetic properties of thin films
- Magnetic Properties of Alloys
- Superconductivity in MgB2 and Alloys
- Plasma Diagnostics and Applications
- Atomic and Molecular Physics
- Muon and positron interactions and applications
- Inorganic Fluorides and Related Compounds
- Topological Materials and Phenomena
- Crystal Structures and Properties
- Theoretical and Computational Physics
- Inorganic Chemistry and Materials
- High-pressure geophysics and materials
- Particle accelerators and beam dynamics
- Nuclear Materials and Properties
- Superconducting Materials and Applications
- Solid-state spectroscopy and crystallography
- Particle physics theoretical and experimental studies
- Crystallization and Solubility Studies
McMaster University
2018-2024
Hamilton Health Sciences
2024
Neutron scattering measurements on the pyrochlore magnet Ce2Zr2O7 reveal an unusual crystal field splitting of its lowest J=5/2 multiplet, such that ground-state doublet is composed mJ=±3/2, giving these doublets a dipole-octupole (DO) character with local Ising anisotropy. Its magnetic susceptibility shows weak antiferromagnetic correlations θCW=−0.4(2) K, leading to naive expectation all-in, all-out ordered state at low temperatures. Instead, our low-energy inelastic neutron show dynamic...
The Ce3+ pseudospin-1/2 degrees of freedom in the pyrochlore magnet Ce2Zr2O7 are known to possess dipole-octupole character, making it a candidate for novel quantum spin liquid ground states at low temperatures. We report new polarized neutron diffraction temperatures, as well heat capacity (Cp) measurements on single crystal Ce2Zr2O7. former bears both similarities and differences with that measured from canonical dipolar ice compound Ho2Ti2O7, while latter rises sharply initially...
Iron-chalcogenide superconductors FeSe 1− x S possess unique electronic properties such as nonmagnetic nematic order and its quantum critical point. The nature of superconductivity with nematicity is important for understanding the mechanism unconventional superconductivity. A recent theory suggested possible emergence a fundamentally new class so-called Bogoliubov Fermi surfaces (BFSs) in this system. However, an ultranodal pair state requires broken time-reversal symmetry (TRS)...
The pyrochlore magnet ${\mathrm{Ce}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ has attracted much attention as a quantum spin ice candidate whose novelty derives in part from the dipolar-octupolar nature of ${\mathrm{Ce}}^{3+}$ pseudospin-1/2 degrees freedom it possesses. We report heat capacity measurements on single crystal samples down to $T\ensuremath{\sim}0.1\phantom{\rule{4pt}{0ex}}\mathrm{K}$ magnetic field along $[1,\overline{1},0]$ direction. These show that broad hump zero-field moves...
We report new magnetic heat capacity measurements of a high quality single crystal the dipole-octupole pyrochlore Ce$_2$Hf$_2$O$_7$ down to temperature $T = 0.02$ K, factor three lower than those previously reported. These show two-peaked structure, with Schottky-like peak at $T_1 \sim 0.065$ similar what is observed in its sister Ce-pyrochlores Ce$_2$Zr$_2$O$_7$ and Ce$_2$Sn$_2$O$_7$. However second, sharper $T_2 0.025$ which signifies entrance ground state, as even most abrupt...
We present muon spin rotation and relaxation $(\ensuremath{\mu}\mathrm{SR})$ measurements as well demagnetizing-field-corrected magnetization on polycrystalline samples of the noncentrosymmetric superconductor BeAu. From $\ensuremath{\mu}\mathrm{SR}$ in a transverse field, we determine that BeAu is type-I with H${}_{c}=$ 258 Oe, amending previous understanding compound type-II superconductor. To account for demagnetizing effects measurements, produce an ellipsoidal sample, which...
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 report a chemical substitution-induced ferromagnetic quantum critical point in polycrystalline ${\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Rh}}_{x}$ alloys. Through magnetization and muon spin relaxation measurements, we show that the ordering temperature is suppressed continuously to zero at ${x}_{\mathrm{crit}}=0.375$ while magnetic volume fraction remains 100% up ${x}_{\mathrm{crit}}$, pointing second order transition. Non-Fermi liquid behavior observed close where electronic specific...
Underlying disorder in skyrmion materials may both inhibit and facilitate reorientations changes topology. The identification of these disorder-induced topologically active regimes is critical to realizing robust spintronic implementations, yet few studies exist for disordered bulk samples. Here, we employ small-angle neutron scattering (SANS) micromagnetic simulations examine the influence order on lattice formation, transition, reorientation dynamics across phase space a polycrystalline...
We have studied the superconducting properties of isostructural ternary noncentrosymmetric superconductors $\mathrm{Ta}X\mathrm{Si}$ $(X=\mathrm{Re}, \mathrm{Ru})$ with help muon spin rotation/relaxation $(\ensuremath{\mu}\mathrm{SR})$ and density functional theory calculations. Our transverse-field $\ensuremath{\mu}\mathrm{SR}$ measurements indicate isotropic $s$-wave superconductivity in TaReSi multigap TaRuSi. Zero-field measurements, highly sensitive to very small magnetic fields, find...
Topologically non trivial spin textures host great promise for future spintronic applications. Skyrmions in particular are of burgeoning interest owing to their nanometric size, topological protection, and high mobility via ultra-low current densities. It has been previously reported through magnetic susceptibility, microscopy, scattering techniques that Co$_{8}$Zn$_{8}$Mn$_{4}$ forms an above room temperature triangular skyrmion lattice. Here we report the synthesis procedure...
Iridates with the $5{d}^{4}$ electronic configuration have attracted recent interest due to reports of magnetically ordered ground states despite longstanding expectations that their strong spin-orbit coupling would generate a $J=0$ state for each ${\mathrm{Ir}}^{5+}$ ion. The major focus prior research has been on double perovskite iridates ${\mathrm{Ba}}_{2}{\mathrm{YIrO}}_{6}$ and ${\mathrm{Sr}}_{2}{\mathrm{YIrO}}_{6}$, where nature (i.e., vs nonmagnetic) is still controversial. Here, we...
The ${\mathrm{Ce}}^{3+}$ pseudospin-$1/2$ degrees of freedom in ${\mathrm{Ce}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ possess both dipolar and octupolar character which enables the possibility novel quantum spin liquid ground states this material. Here we report muon relaxation rotation ($\ensuremath{\mu}\mathrm{SR}$) measurements on single-crystal samples zero magnetic field fields directed along $[1,\overline{1},0]$ $[1,1,1]$ crystallographic directions, for longitudinal transverse to...
We present the synthesis and physical properties of a breathing pyrochlore magnet ${\mathrm{CuAlCr}}_{4}{\mathrm{S}}_{8}$ via synchrotron x-ray diffraction, magnetization under ambient applied hydrostatic pressure, heat capacity, muon spin relaxation/rotation measurements. exhibits positive thermal expansion with concave upward temperature dependence. observed sharp antiferromagnetic ordering transition purely magnetic nature at 20 K, which shifts by as much 3.2 K on application 600 MPa...
Abstract The emission of muonium ($\mu^+e^-$) atoms into vacuum from silica aerogel with laser ablation on its surface was studied various structures at room temperature using the subsurface muon beams TRIUMF and Japan Proton Accelerator Research Complex (J-PARC). Laser applied to produce holes or grooves typical dimensions a few hundred $\mu$m mm, except for some extreme conditions. measured rate tends be higher larger fractions opening shallower depths. More than reach rates similar...
Here, the authors report on superconducting properties of ternary noncentrosymmetric superconductor Re${}_{8}$NbTa, a new member Re-based superconductors that are known for frequent occurrence time-reversal symmetry breaking and their complex ground states. Bulk transverse field muon spin rotation/relaxation (\ensuremath{\mu}SR) measurements confirm moderately coupled, fully gapped superconductivity. However, zero-field \ensuremath{\mu}SR indicate possible presence fluctuation/time-reversal...
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...
We present a comprehensive study on superconducting properties of Re$_7$B$_3$ and Re$_3$B through specific heat, magnetic susceptibility, resistivity, transverse zero-field muon spin rotation/relaxation ($\mu$SR) experiments polycrystalline samples. (T$_C$ = 3.2~K) is non-centrosymmetric type-II ($\kappa$ $\approx$ 9.27) superconductor in the weak coupling ($\lambda_{e-ph}$ 0.54) regime. On other hand, 5.19~K) centrosymmetric 34.55) moderate 0.64) Our transverse-field $\mu$SR measurements...
We present a muon spin relaxation study of the Mott transition in BaCoS_2 using two independent control parameters: (i) pressure p to tune electronic bandwidth and (ii) Ni-substitution x on Co site band filling. For both tuning parameters, antiferromagnetic insulating state first transitions an metal finally paramagnetic without undergoing any structural phase transition. under displays minimal change ordered magnetic moment S_ord until it collapses abruptly upon entering metallic at p_cr ~...
We have investigated the superconducting properties in a single crystal of new superconductor Pb$_{2}$Pd via various techniques including magnetization, AC transport, transverse field muon spin rotation and relaxation (TF-$\mu$SR), heat capacity. crystallizes body-centred tetragonal structure with space group I4/$mcm$. All measurements confirm transition temperature, T$_{C}$ = 3.0 $\pm$ 0.1 K. Electronic specific data are well described by BCS fitting, suggesting that opens an isotropic gap...
We report the discovery of ${\mathrm{Ce}}_{3}{\mathrm{Ir}}_{4}{\mathrm{Ge}}_{13}$, a Remeika phase with complex array structural, electronic, and magnetic properties. Our single crystal x-ray diffraction measurements show that ${\mathrm{Ce}}_{3}{\mathrm{Ir}}_{4}{\mathrm{Ge}}_{13}$ forms in tetragonally distorted $I{4}_{1}/amd$ space group, which has three distinct rare earth sites. The electrical resistivity is almost temperature independent over decades temperature, from 0.4 K to 400 K,...
Valence-skipped superconductors are natural candidates for unconventional superconductivity because they can exhibit a negative effective, attractive interaction electron pairing. This work reports comprehensive x-ray diffraction, magnetization, specific heat, and muon spin rotation relaxation measurements ($\ensuremath{\mu}\mathrm{SR}$) on the valence-skipped compound ${\mathrm{AgSnSe}}_{2}$. The temperature dependences of electronic heat $[{C}_{\mathrm{el}}(T)]$ upper critical field...
We report new heat capacity measurements on single crystal Ce$_2$Zr$_2$O$_7$ down to $\sim$ 0.1 K in a magnetic field along the $[1,\bar{1}, 0]$ direction. These show that broad hump zero-field moves higher temperature with increasing strength and is split into two humps by at 2 T. separate features are due decomposition of pyrochlore lattice effectively decoupled chains for fields this direction: one set ($\alpha$-chains) polarized while other ($\beta$-chains) remains free. Our theoretical...
Abstract New phases of matter emerge at the edge magnetic instabilities, which can occur in materials with moments that are localized, itinerant or intermediate between these extremes. In local moment systems, such as heavy fermions, magnetism be tuned towards a zero-temperature transition quantum critical point (QCP) via pressure, chemical doping, and, rarely, field. By contrast, QCPs more rare, and they induced by pressure doping; there no known examples field transitions. This means...
Geometric magnetic frustration (GMF) has attracted substantial interest due to the exotic physics and rich phase diagrams revealed by cancellation of normally-dominant interactions, giving impetus for search novel frustrated systems, most often based on antiferromagnetic correlations between ions decorating triangular or tetrahedral lattices. We report here low-temperature susceptibility muon spin relaxation results Li4MgOsO6 Li3Mg2OsO6, members A5BO6 "rock salt ordered" family materials. In...