A5017930902- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Advanced NMR Techniques and Applications
- Muon and positron interactions and applications
- Rare-earth and actinide compounds
- Magnetic and transport properties of perovskites and related materials
- Advancements in Battery Materials
- Magnetic properties of thin films
- Atomic and Subatomic Physics Research
- NMR spectroscopy and applications
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Magnetic Properties of Alloys
- Iron-based superconductors research
- Ammonia Synthesis and Nitrogen Reduction
- Graphene research and applications
- Particle accelerators and beam dynamics
- Quantum, superfluid, helium dynamics
- Superconductivity in MgB2 and Alloys
- Advanced Battery Materials and Technologies
- Quantum and electron transport phenomena
- Material Dynamics and Properties
- Crystallography and Radiation Phenomena
- Solid-state spectroscopy and crystallography
- Atomic and Molecular Physics
TRIUMF
2015-2024
University of British Columbia
1995-2023
Simon Fraser University
2023
University of Victoria
2023
Vancouver Biotech (Canada)
2018-2020
Trimble (Germany)
2012
University of Alberta
2007-2011
Los Alamos National Laboratory
2002-2007
Rutherford Appleton Laboratory
2007
University of Oxford
2007
Positive muons injected into solid ${\mathrm{C}}_{60}$, ${\mathrm{K}}_{4}$${\mathrm{C}}_{60}$, and ${\mathrm{K}}_{6}$${\mathrm{C}}_{60}$ form vacuumlike muonium (${\mathrm{\ensuremath{\mu}}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$) with a (6--12)% probability. Observation of coherent spin precession establishes that all three materials are nonmagnetic nonconducting at low temperatures. From the temperature dependence signals we estimate electronic band gaps in...
Transverse-field muon-spin rotation measurements in the vortex-lattice of heavy-fermion (HF) superconductor PrOs4Sb12 yield a temperature dependence magnetic penetration depth lambda indicative an isotropic or nearly energy gap. This is not seen to date any other HF and signature pairing symmetry, possibly related novel nonmagnetic "quadrupolar Kondo" mechanism PrOs4Sb12. The T=0 relaxation rate sigma(s)(0)=0.91(1) micros(-1) yields estimated lambda(0)=3440(20) A, which considerably shorter...
For some time now, there has been considerable experimental and theoretical effort to understand the role of normal-state "pseudogap" phase in underdoped high-temperature cuprate superconductors. Recent debate centered on question whether pseudogap is independent superconductivity. We provide evidence from zero-field muon spin relaxation measurements YBa2Cu3O6+x for presence small spontaneous static magnetic fields electronic origin intimately related transition. Our most significant finding...
Evidence for static alternating magnetic fields in the vortex cores of underdoped YBa2Cu3O6+x is reported. Muon spin rotation measurements internal field distribution state YBa2Cu3O6.50 applied H = 1 T and 4 reveal a feature high-field tail which not present optimally doped YBa2Cu3O6.95 fits well to model with cores. The magnitude estimated be 18(2) G decreases above 10 K. We discuss possible origins additional core magnetism within context existing theories.
The antiferromagnetic (AF) nature of the normal spinel ${\mathrm{Co}}_{3}{\mathrm{O}}_{4}$ with N\'eel temperature $({T}_{\mathrm{N}})=30\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ was investigated by means positive muon spin rotation and relaxation $({\ensuremath{\mu}}^{+}\mathrm{SR})$ techniques using a polycrystalline sample. Clear precession signals due to quasistatic long-range AF order were found in zero-field ${\ensuremath{\mu}}^{+}\mathrm{SR}$ spectra below ${T}_{\mathrm{N}}$. consist two...
Muon relaxation experiments reveal a slowly fluctuating magnetic field in the pseudogap phase of cuprate superconductor.
Depth-controlled $\ensuremath{\beta}$-NMR can be used to probe the magnetic properties of thin films and interfaces on a nanometer length scale. A 30 keV beam highly spin-polarized $^{8}\mathrm{L}\mathrm{i}^{+}$ ions was slowed down implanted into 50 nm film Ag deposited ${\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_{3}$ substrate. novel high field spectrometer observe two well resolved resonances which are attributed Li occupying substitutional octahedral interstitial sites in...
The magnetic properties of ${\mathrm{YBa}}_{2}$(${\mathrm{Cu}}_{0.96}$${\mathrm{Zn}}_{0.04}$${)}_{3}$${\mathrm{O}}_{\mathit{x}}$ were studied in detail by means muon spin rotation and relaxation for 6.0\ensuremath{\le}x\ensuremath{\le}6.92. complete phase diagram was mapped out a disordered state found to persist between x=6.4 x\ensuremath{\simeq}6.7 (metallic transition), contrast with pure ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{\mathit{x}}$. appearance this is attributed the...
Muon spin relaxation measurements in liquid neon electric fields up to 35 kV/cm reveal two types of radiolysis electrons created the positive muon's ionization track. Some these are initially delocalized (fast) and reach ${\ensuremath{\mu}}^{+}$ form a muonium atom before they can become localized (slow) inside bubbles. Fast slow have similar initial spatial distributions relative thermalized muon.
Magnetism of the simplest layered cobaltite ${\mathrm{Li}}_{x}{\mathrm{CoO}}_{2}$ with $x=1.0$, 0.95, and 0.7 has been investigated by positive muon spin rotation relaxation $({\ensuremath{\mu}}^{+}\mathrm{SR})$ spectroscopy together magnetic susceptibility measurements, using polycrystalline samples in temperature range between 300 1.8 K. Weak transverse field ${\ensuremath{\mu}}^{+}\mathrm{SR}$ showed appearance magnetism below...
The magnetic properties of a monolayer Mn12 single molecule magnets grafted onto silicon (Si) substrate have been investigated using depth-controlled β-detected nuclear resonance. A low-energy beam spin-polarized radioactive 8Li was used to probe the local static field distribution near in Si substrate. resonance line width varies strongly as function implantation depth result dipolar fields generated by electronic moments. temperature dependence indicates that moments this low-dimensional...
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...
Experimental studies of excess electron transport in solid and liquid phases Ne Ar are presented compared with those for He. The technique muon spin relaxation frequently reversed electric fields was used to study the phenomenon delayed muonium formation, whereby electrons liberated ${\ensuremath{\mu}}^{+}$ ionization track converge upon positive muons form ${\ensuremath{\mu}}^{+}{e}^{\ensuremath{-}}$ atoms. This process is shown be crucially dependent electron's interaction its environment...
A direct measurement of the London penetration depth in high-${T}_{c}$ superconductor ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{6.92}$ has been made using low-energy $\ensuremath{\mu}\text{SR}$ with an effective background suppression method. The average magnetic field versus mean was measured Meissner state high-purity detwinned crystals ${\text{YBa}}_{2}{\text{Cu}}_{3}{\text{O}}_{6.92}$. resulting profiles along $a$ and $b$ axes are consistent a local model beyond 10 nm but there...
We report the NMR Knight shift and spin-lattice relaxation of $^{8}\mathrm{Li}{}^{+}$ implanted $\ensuremath{\sim}100$ nm into single crystals semimetallic Sb, Bi, topologically insulating ${\mathrm{Bi}}_{0.9}{\mathrm{Sb}}_{0.1}$. find small negative shifts (of order 100 ppm) in all three. In insulator, is nearly temperature independent, while Bi Sb it becomes more at low without following bulk susceptibility, suggesting two distinct dependent contributions, possibly from orbital spin...
We report muon spin rotation measurements in $n$-type silicon from 10 to 310 K electric fields up 5 kV/cm. These experiments reveal the nature of partition neutral muonium centers into normal $({\mathrm{Mu}}_{T}^{0})$ and anomalous $({\mathrm{Mu}}_{\mathrm{BC}}^{0})$: Formation ${\mathrm{Mu}}_{T}^{0}$ is consistent with epithermal processes prior thermalization, while ${\mathrm{Mu}}_{\mathrm{BC}}^{0}$ formed via electron transport a thermalized positive muon. The spatial distribution excess...
β-Detected nuclear spin relaxation of (8)Li(+) has been used to study the microscopic diffusion lithium ions in thin films poly(ethylene oxide) (PEO), where implanted are present extremely low concentration, and PEO with 30 wt % LiCF3SO3 over a wide range temperatures both above below glass transition temperature. Recent measurements by Do et al. [Phys. Rev. Lett. 2013, 111, 018301] found that temperature dependence Li(+) conductivity was identical dielectric α well described...
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...
Magnetic, specific heat, and structural properties of the equiatomic Cantor alloy system are reported for temperatures between 5 300 K, up to fields 70 kOe. Magnetization measurements performed on as-cast, annealed, cold-worked samples reveal a strong processing history dependence that high-temperature annealing after cold working does not restore ``pristine'' state. Measurements known precipitates show two transitions, detected at 43 85 intrinsic result an impurity phase. Experimental ab...
Muon spin relaxation/rotation/resonance ( $$\varvec{\mu \textrm{SR}}$$ ) method is one of the most effective experimental methods and has been used in many fields such as material science, chemical, bioscience since 1970s. For next elevation , we developed positron detectors that have a spatial resolution them trackers so could construct an image sample. Demonstrative experiments were performed at TRIUMF sample was successfully reconstructed.
Manganese telluride (MnTe) is a prospective platform for ultrafast carrier dynamics, spin-based thermoelectrics, and magnon-drag transport due to its unique electronic magnetic properties. We use inelastic neutron scattering study both pure lithium-doped MnTe, focusing on the influence of doping in opening magnon gap. powder diffraction determine critical exponents phase transition Li-doped MnTe complement this information with muon spin rotation/relaxation. The gap reorientation mainly...