A5054818798- Ionic liquids properties and applications
- Advanced Condensed Matter Physics
- Particle accelerators and beam dynamics
- Advancements in Battery Materials
- Advanced NMR Techniques and Applications
- Material Dynamics and Properties
- Magnetic and transport properties of perovskites and related materials
- Thermal Expansion and Ionic Conductivity
- Muon and positron interactions and applications
- NMR spectroscopy and applications
- Solid-state spectroscopy and crystallography
- Electron and X-Ray Spectroscopy Techniques
- ZnO doping and properties
- Rare-earth and actinide compounds
- Electronic and Structural Properties of Oxides
- Inorganic Chemistry and Materials
- Graphite, nuclear technology, radiation studies
- Plasma Diagnostics and Applications
- Crystallography and Radiation Phenomena
- Ion-surface interactions and analysis
- 2D Materials and Applications
- Microwave Dielectric Ceramics Synthesis
- Digital Rights Management and Security
- Thermodynamic and Structural Properties of Metals and Alloys
- Thermodynamic properties of mixtures
University of British Columbia
2019-2024
TRIUMF
2023-2024
Simon Fraser University
2023
University of Victoria
2023
Vancouver Biotech (Canada)
2020
Georgia Institute of Technology
2018
Currently, no known material retains its photoinduced metallic conductivity over a long time while also exhibiting repeatable metal-to-insulator recovery. Here, we demonstrate such highly insulator-to-metal transition in yttrium oxyhydride (YOxHy) epitaxial thin films. The temperature (T) dependence of the electrical resistivity (ρ) films transforms from insulating to state (dρ/dT > 0) under ultraviolet laser illumination. YOxHy film recovers original when heated (125 °C) an Ar atmosphere...
A new high field spectrometer has been built to extend the capabilities of $\beta$-detected nuclear magnetic resonance ($\beta$-NMR) facility at TRIUMF. This beamline extension allows $\beta$-NMR spectroscopy be performed with fields up 200 mT parallel a sample's surface (perpendicular ion beam), allowing depth-resolved studies local electromagnetic spin polarized probes much higher applied than previously available in this configuration. The primary motivation and application is allow...
We investigated the depth, temperature, and molecular-weight (MW) dependence of γ-relaxation in polystyrene glasses using implanted 8Li+ β-detected nuclear magnetic resonance. Measurements were performed on thin films with MW ranging from 1.1 to 641 kg/mol. The temperature average 8Li spin-lattice relaxation time (T1avg) was measured near free surface bulk. Spin-lattice is caused by phenyl ring flips, which involve transitions between local minima over free-energy barriers enthalpic entropic...
Heat treatment of cubic YbZrF7, after quenching from 1000 °C, leads to a material displaying precisely zero thermal expansion at ∼300 K and negative lower temperatures. The is associated with minimum in the lattice constant K. X-ray total scattering measurements are consistent previously proposed model which incorporation interstitial fluoride into ReO3-related structure both edge corner sharing coordination polyhedra. temperature dependence experimental pair correlation functions suggests...
We report $\ensuremath{\beta}$-detected NMR of ion-implanted $^{8}\mathrm{Li}$ in a single crystal and thin film the strongly correlated metal ${\mathrm{LaNiO}}_{3}$. Spin-lattice relaxation measurements reveal two distinct local environments, both metallic as evident from $T$-linear Korringa $1/{T}_{1}$ below $200\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ with slopes comparable to other metals. A small approximately temperature-independent Knight shift...
We demonstrate the application of implanted-ion $\beta$-detected NMR as a probe ionic liquid molecular dynamics through measurement $^8$Li spin-lattice relaxation (SLR) and resonance in 1-ethyl-3-methylimidazolium acetate. The motional narrowing resonance, local maxima SLR rate, $1/T_1$, imply sensitivity to sub-nanosecond Li$^+$ solvation dynamics. From an analysis we extract activation energy ${E_A = 74.8 \pm 1.5}$ meV Vogel-Fulcher-Tammann constant ${T_{\mathrm{VFT}} 165.8 0.9}$ K,...
We report on the stability and magnetic state of ion implanted $^{8}\mathrm{Li}$ in single crystals semiconductor ZnO using $\ensuremath{\beta}$-detected nuclear resonance. At ultradilute concentrations, spectra reveal distinct Li sites from 7.6 to 400 K. Ionized shallow donor interstitial is stable across entire temperature range, confirming its ability self-compensate acceptor character (Zn) substitutional counterpart. Above 300 K, spin-lattice relaxation indicates onset correlated local...
We report direct measurements of the magnetic field screening at limits Meissner phase for two superconducting Nb samples. The samples are processed with different surface treatments that have been developed radio-frequency cavity applications -- a "baseline" treatment and an oxygen-doping ("O-doping") treatment. show: 1) length is significantly longer in "O-doping" sample compared to sample; 2) near increases applied field; 3) evolution profile as material transitions from mixed phase; 4)...
<title>Abstract</title> We report direct measurements of the magnetic field screening at limits Meissner phase for two superconducting Nb samples. The samples are processed with different surface treatments that have been developed radio-frequency cavity applications — a “baseline” treatment and an oxygen-doping (“O-doping” ) treatment. show: 1) length is significantly longer in “O-doping” sample compared to sample; 2) near increases applied field; 3) evolution profile as material...
Abstract We present high (> 2 T) magnetic field β NMR measurements of 8 Li + implanted in single crystals sapphire, a commonly used backing material for other samples. From the well-resolved quadrupolar splitting, we extract electric gradient (EFG) at site. Comparison with supercell density functional theory calculations EFG allows us to identify octahedral interstitial site as most likely candidate. In contrast zero NQR spectra, where multiple singals are detected, only is evident field....
We report $\ensuremath{\beta}$-detected nuclear magnetic resonance of ultradilute $^{8}\mathrm{Li}^{+}$ implanted in highly oriented pyrolytic graphite (HOPG). The absence motional narrowing and diffusional spin-lattice relaxation implies ${\mathrm{Li}}^{+}$ is not appreciably mobile up to 400 K, sharp contrast the lithiated stage compounds. However, remarkably fast persists down cryogenic temperatures. Ruling out extrinsic paramagnetic impurities intrinsic ferromagnetism, we conclude due...
We report the first nuclear magnetic resonance measurements of an atypical transition metal dichalcogenide, CrSe<sub>2</sub>.
We report measurements of the diffusion rate isolated ion-implanted $^{8}$Li$^{+}$ within $\sim$120 nm surface oriented single-crystal rutile TiO$_2$ using a radiotracer technique. The $\alpha$-particles from $^{8}$Li decay provide sensitive monitor distance and how depth profile evolves with time. main findings are that implanted Li$^{+}$ diffuses traps at (001) surface. T-dependence diffusivity is described by bi-Arrhenius expression activation energies 0.3341(21) eV above 200 K, whereas...
We report $\beta$-detected nuclear magnetic resonance of ultra-dilute $^{8}$Li$^{+}$ implanted in highly oriented pyrolytic graphite (HOPG). The absence motional narrowing and diffusional spin-lattice relaxation implies Li$^+$ is not appreciably mobile up to 400 K, sharp contrast the lithiated stage compounds. However, remarkably fast persists down cryogenic temperatures. Ruling out extrinsic paramagnetic impurities intrinsic ferromagnetism, we conclude due centers correlated with...
Abstract We report the β -detected NMR of implanted 8 Li + in rhombohedrally distorted perovskite LaAlO 3 . As observed other insulating perovskites, resonance has large quadrupolar splitting. However, it exhibits additional splitting due to rhombohedral distortion. In addition, magnitude electric field gradient at site is larger than cubic such as SrTiO , with v Q ≈ 191.3 kHz.
Abstract In our prior work, we showed that β -detected nuclear magnetic resonance ( -NMR) was a good probe of bulk room temperature ionic liquid (RTIL) dynamics and dynamic heterogeneity. We now investigate how the surface modifies these properties, presenting first depth-resolved -NMR measurements in 1-ethyl-3-methylimidazolium acetate as liquid, supercooled glass. This interfacial region is important for understanding constrained dimensionality affects dynamics. show both glass transition...
Abstract The inverse perovskite Sr 3 SnO is a 3D cubic Dirac semimetal with very small energy gap[1]. Its unusual electronic structure confers variety of novel properties, such as chiral topological surface states, and strong itinerant electron orbital magnetism. Remarkably, when doped it also becomes superconducting[2]. In the lowest carrier density samples, Fermi level lies close to points, magnetism maximal. Here we report results ion-implanted 8 Li + β NMR in Au-capped epitaxial thin...
A new high field spectrometer has been built to extend the capabilities of $β$-detected nuclear magnetic resonance ($β$-NMR) facility at TRIUMF. This beamline extension allows $β$-NMR spectroscopy be performed with fields up 200 mT parallel a sample's surface (perpendicular ion beam), allowing depth-resolved studies local electromagnetic spin polarized probes much higher applied than previously available in this configuration. The primary motivation and application is allow superconducting...