A5011041363- GaN-based semiconductor devices and materials
- ZnO doping and properties
- Rare-earth and actinide compounds
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
- Inorganic Chemistry and Materials
- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Boron and Carbon Nanomaterials Research
- Quantum and electron transport phenomena
- Electronic and Structural Properties of Oxides
- Viral gastroenteritis research and epidemiology
- Magnetic and transport properties of perovskites and related materials
- Ga2O3 and related materials
- Advanced Chemical Physics Studies
- Heusler alloys: electronic and magnetic properties
- Semiconductor Quantum Structures and Devices
- Catalytic Processes in Materials Science
- Advanced Electrical Measurement Techniques
- Ammonia Synthesis and Nitrogen Reduction
- Thin-Film Transistor Technologies
- Gas Sensing Nanomaterials and Sensors
- Theoretical and Computational Physics
- Animal Virus Infections Studies
- Copper-based nanomaterials and applications
Victoria University of Wellington
2016-2025
MacDiarmid Institute for Advanced Materials and Nanotechnology
2016-2025
Victoria University
2013
Victoria University
2012
GNS Science
2009
Australian National University
2008
Macquarie University
2008
ACT Government
2008
University of British Columbia
2001-2002
Forschungszentrum Jülich
1996-1999
We report the results from magnetic, resistivity, and Hall effect measurements on a ferromagnetically ordered 5% Gd low energy implanted ZnO single crystal. Temperature-dependent magnetization show that ions do not contribute to magnetic order; hence, order is intrinsic. The electronic transport in Gd-implanted region inhomogeneous, there nonlinear resistance. resistance likely be consequence of inhomogeneous due an anomalous effect.
We report the growth of $\mathrm{GdN}$ thin films and a study their structure magnetic conducting properties. It is demonstrated that they are semiconducting at ambient temperature with nitrogen vacancies dominant dopant. The ferromagnetic below $68\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, significant narrowing band gap signaled by more than doubling its conductivity. conductivity in low-temperature state remains typical doped semiconductor, supporting view this material ground no...
We report measurements of the optical gap in a GdN film at temperatures from $300\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, covering both paramagnetic and ferromagnetic phases. The is $1.31\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ phase redshifts to $0.9\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ spin-split bands below Curie temperature. larger than was suggested by very early experiments, has permitted us refine...
We present the structural and photoluminescence properties of 30 keV gadolinium implanted subsequently annealed zinc oxide (ZnO) single crystals. Rutherford backscattering channeling results reveal a low surface region defect density which was reduced further upon annealing. For implantation fluence, around 85% Gd atoms are estimated to be in sites aligned with ZnO lattice, while for higher fluences is largely disordered likely forms precipitates. The Raman spectra samples show...
The band nonparabolicity of indium tin oxide (ITO) polycrystalline thin films is investigated with the quasilinear Kane model through Seebeck and Hall effect measurements. We report nonparabolic parameters ${m}_{0}^{*}=0.21\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}_{0}$ $C=0.52\phantom{\rule{0.16em}{0ex}}{\mathrm{eV}}^{\text{\ensuremath{-}}1}$ for ITO, in good agreement historical photoemission, optical, transport To do this, ITO were doped nitrogen by ion implantation, fluences ranging from...
Soft x-ray emission and absorption spectroscopy of the $\text{O}\text{ }K$-edge are employed to investigate electronic structure wurtzite ZnO(0001). A quasiparticle band calculated within $GW$ approximation agrees well with data, most notably energetic location $\text{Zn}\text{ }3d--\text{O}\text{ }2p$ hybridized state anisotropy spectra. Dispersion in is mapped using coherent $\mathbf{k}$-selective part resonant We show that a more extensive mapping bands possible case crystalline such as found ZnO.
Epitaxial gadolinium nitride films with well-oriented crystallites of up to 30 nm have been grown on yttria-stabilized ziconia substrates using a plasma-assisted pulsed laser deposition technique. We observe that the epitaxial GdN growth proceeds top oxide buffer layer forms via reaction between deposited Gd and mobile oxygen from substrate. Hall effect measurements show are electron doped degeneracy, carrier concentrations 4×1020 cm−3. Magnetic establish TC 70 K coercive field can be tuned...
Electron microscopy od duodenal mucosa from children with acute non-bacterial enteritis has shown virus particles in epithelial cells. Indirect immunofluorescent techniques applied to the same tissue showed antigen localized cytoplasm of cells villi. Specific IgM antibody was present sera infected patients as early two days after onset symptoms. Virus different appeared share a common antigen. The evidence presented supports our belief that this new cause studied.
Ferromagnetic order is observed in Gd ion implanted ZnO crystals after annealing at 650 °C a vacuum and we find that it intrinsic extends to depths of up 40 nm. The ferromagnetic not affected by for concentrations as high 5% possibly arises from defect clusters. Magnetoresistance low temperatures may be due spin-tunnelling between the clusters or spin-dependent scattering cluster interfaces. implantation has an advantageous effect where results mΩ cm resistivities well significant electron doping.
Here we report a new, bench-top synthesis for iron/iron oxide core/shell nanoparticlesvia the thermal decomposition of Fe(η5-C6H3Me4)2. The nanoparticles are superparamagnetic at room temperature and show improved negative contrast in T2-weighted MR imaging compared to pure iron oxides nanoparticles, have transverse relaxivity (r2) 332 mM−1 s−1.
Polycrystalline GdN thin films have been grown at room temperature with varying N2 pressure. By the nitrogen pressure during growth we alter carrier concentrations of films. Films low pressures display onset magnetization temperatures as high 200 K and a resistivity 0.3 mΩ cm, whereas all show Curie very close to 70 ranges over 1–1000 Ω cm are observed. For peak in occurs TC.
Magnetic skyrmions are topologically protected spin textures with great technological potential. These non-trivial non-coplanar give rise to a topological Hall effect, enabling the purely electronic detection of magnetic skyrmions. We report clear effect in thin films Heusler alloy Mn2CoAl, ferromagnetic spin-gapless semiconductor, capped by layer Pd. exploit strong thickness- and temperature-dependence anomalous this system, tuning it zero enable unambiguous measurement which is observed...
SmN is ferromagnetic below 27 K, and its net magnetic moment of 0.03 Bohr magnetons per formula unit one the smallest magnetizations found in any material. The near-zero a result nearly equal opposing spin orbital moments ${}^{6}$H${}_{5/2}$ ground state Sm${}^{3+}$ ion, which leads finally to complete cancellation for an ion state. Here we explore alignment this compound with x-ray circular dichroism at Sm L${}_{2,3}$ edges. spectral shapes are qualitative agreement computed spectra based...
We investigate the electronic band structure of two rare-earth nitrides, DyN and SmN. Resistivity measurements imply that both materials have a semiconducting ground state, show resistivity anomalies coinciding with magnetic transition, despite different states in X-ray absorption emission are excellent agreement densities obtained from $\mathrm{LSDA}+U$ calculations, although for SmN calculations predict zero gap.
The magnetic behavior of SmN has been investigated in stoichiometric polycrystalline films. All samples show ferromagnetic order with Curie temperature $({T}_{C})$ $27\ifmmode\pm\else\textpm\fi{}3\text{ }\text{K}$, evidenced by the occurrence hysteresis below ${T}_{C}$. state is characterized a very small moment and large coercive field, exceeding even maximum applied field 6 T about 15 K. residual magnetization at 2 K, measured after cooling $0.035{\ensuremath{\mu}}_{B}$ per Sm. Such...