A5057363429- ZnO doping and properties
- Magnetic properties of thin films
- Magnetic and transport properties of perovskites and related materials
- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Physics of Superconductivity and Magnetism
- Electronic and Structural Properties of Oxides
- Ga2O3 and related materials
- Quantum and electron transport phenomena
- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Semiconductor materials and devices
- Multiferroics and related materials
- Magnetic Properties and Applications
- Metal and Thin Film Mechanics
- Acoustic Wave Resonator Technologies
- Terahertz technology and applications
- Magneto-Optical Properties and Applications
- Nanowire Synthesis and Applications
- Advanced Memory and Neural Computing
- Mechanical and Optical Resonators
- Advanced Condensed Matter Physics
- Magnetic Field Sensors Techniques
- Advanced Chemical Physics Studies
University of Nottingham
2015-2024
Czech Academy of Sciences, Institute of Physics
2010-2022
Rutherford Appleton Laboratory
1993-2022
Czech Academy of Sciences
2022
University of Liverpool
1993-2021
Diamond Light Source
2012
Tokyo Metropolitan University
2010
MacDiarmid Institute for Advanced Materials and Nanotechnology
2010
École Polytechnique Fédérale de Lausanne
2010
Honeywell (United States)
2010
Manipulating a stubborn magnet Spintronics is an alternative to conventional electronics, based on using the electron's spin rather than its charge. Spintronic devices, such as magnetic memory, have traditionally used ferromagnetic materials encode 1's and 0's of binary code. A weakness this approach—that strong fields can erase encoded information—could be avoided by antiferromagnets instead ferromagnets. But manipulating ordering tricky. Now, Wadley et al. found way (see Perspective...
We present a combined theoretical and experimental study of the ferromagnetic semiconductor (Ga,Mn)As which explains remarkably large changes observed on low-temperature annealing. Careful control annealing conditions allows us to obtain samples with transition temperatures up 159 K. Ab initio calculations, in situ Auger spectroscopy, resistivity measurements during show that are due out diffusion Mn interstitials towards surface, governed by an energy barrier 0.7-0.8 eV. Electric fields...
We report on a comprehensive combined experimental and theoretical study of Curie temperature trends in (Ga,Mn)As ferromagnetic semiconductors. Broad agreement between expectations measured data allows us to conclude that ${T}_{c}$ high-quality metallic samples increases linearly with the number uncompensated local moments ${\mathrm{Mn}}_{\mathrm{Ga}}$ acceptors, no sign saturation. Room ferromagnetism is expected for 10% concentration these moments. Our magnetotransport magnetization are...
We demonstrate terahertz electrical writing speed in an antiferromagnetic memory at energy of the gigahertz writing.
The magnetic order in antiferromagnetic materials is hard to control with external fields. Using x-ray linear dichroism microscopy, we show that staggered effective fields generated by electrical current can induce modification of the domain structure microdevices fabricated from a tetragonal CuMnAs thin film. A clear correlation between average orientation and anisotropy resistance demonstrated, both showing reproducible switching response orthogonally applied pulses. However, behavior...
Abstract Antiferromagnets offer a unique combination of properties including the radiation and magnetic field hardness, absence stray fields, spin-dynamics frequency scale in terahertz. Recent experiments have demonstrated that relativistic spin-orbit torques can provide means for an efficient electric control antiferromagnetic moments. Here we show elementary-shape memory cells fabricated from single-layer antiferromagnet CuMnAs deposited on III–V or Si substrate deterministic multi-level...
Altermagnetism is a recently identified magnetic symmetry class combining characteristics of conventional collinear ferromagnets and antiferromagnets, that were regarded as mutually exclusive, enabling phenomena functionalities unparalleled in either the two traditional elementary classes. In this work we use symmetry, ab initio theory, experiments to explore x-ray circular dichroism (XMCD) altermagnetic class. As representative material for our XMCD study choose α-MnTe with compensated...
We show that by annealing Ga1-xMnxAs thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature Tc conductivity can be obtained. is unambiguously determined to 118 K for Mn concentration x=0.05, 140 x=0.06, 120 x=0.08. also identify a clear correlation between room conductivity. The results indicate excess of current values are achievable with improvements growth post-growth conditions.
We show, by superconducting quantum interference device magnetometry, that in (Ga,Mn)As films the in-plane uniaxial magnetic easy axis is consistently associated with particular crystallographic directions and it can be rotated from $[\overline{1}10]$ direction to [110] low-temperature annealing. show this behavior hole-density dependent does not originate surface anisotropy. The presence of anisotropy as well its dependence on hole concentration temperature explained terms...
We study the effects of growth temperature, Ga:As ratio, and postgrowth annealing procedure on Curie temperature TC (Ga,Mn)As layers grown by molecular beam epitaxy. achieve highest values for temperatures very close to two-dimensional–three-dimensional phase boundary. The increase in TC, due removal interstitial Mn annealing, is counteracted a second process, which reduces more effective at higher temperatures. Our results show that it necessary optimize parameters obtain TC.
Over the past two decades, research of (Ga,Mn)As has led to a deeper understanding relativistic spin-dependent phenomena in magnetic systems. It also discoveries new effects and demonstrations unprecedented functionalities experimental spintronic devices with general applicability wide range materials. This is review basic material properties that make favorable test-bed system for spintronics discussion contributions studies context device concepts. Special focus on spin-orbit coupling...
We discuss the character of states near Fermi level in Mn-doped GaAs, as revealed by a survey dc transport and optical studies over wide range Mn concentrations. A thermally activated valence-band contribution to transport, midinfrared peak at energy $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\approx}200\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ ac conductivity, hot photoluminescence spectra indicate presence an impurity band low-doped ($⪡1%$ Mn) insulating GaAs:Mn materials. Consistent...
We observe a singularity in the temperature derivative drho/dT of resistivity at Curie point high-quality (Ga,Mn)As ferromagnetic semiconductors with Tc's ranging from approximately 80 to 185 K. The character anomaly is sharply distinct critical contribution transport conventional dense-moment magnetic and reminiscent transition metal ferromagnets. Within region accessible our experiments, dependence on side can be explained by dominant scattering uncorrelated spin fluctuations. singular...
Describing the origin of uniaxial magnetic anisotropy (UMA) is generally problematic in systems other than single crystals. We demonstrate an in-plane UMA amorphous CoFeB films on GaAs(001) which has expected symmetry interface ferromagnetic GaAs(001), but strength independent of, rather inverse proportion to, film thickness. show that this volume consistent with a bond-orientational anisotropy, propagates interface-induced through thickness film. It explained how, general, mechanism may...
Electrical detection of the 180 deg spin reversal, which is basis operation ferromagnetic memories, among outstanding challenges in research antiferromagnetic spintronics. Analogous effects to giant or tunneling magnetoresistance have not yet been realized multilayers. Anomalous Hall effect (AHE), has recently employed for reversal non-collinear antiferromagnets, limited materials that crystalize symmetry groups. Here we demonstrate electrical N\'eel vector CuMnAs comprises two collinear...
Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls the order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these that potential terahertz dynamics, deflection-free motion improved size scaling due absence stray field. Here we...
We demonstrate that the interplay of in-plane biaxial and uniaxial anisotropy fields in results a spin reorientation transition an anisotropic ac susceptibility which is fully consistent with simple single-domain model. The constants vary, respectively, as square fourth power spontaneous magnetization across whole temperature range up to . weakening at may be technological importance for applications involving thermally assisted switching.
Our experimental and theoretical study of the non-crystalline crystalline components anisotropic magnetoresistance (AMR) in (Ga,Mn)As is aimed at exploring basic physical aspects this relativistic transport effect. The AMR reflects lifetimes holes due to polarized Mn impurities while associated with valence band warping. We find that sign determined by form spin-orbit coupling host relative strengths non-magnetic magnetic contributions impurity potential. develop methods directly yielding...
We demonstrate voltage control of the magnetic anisotropy a (Ga,Mn)As device bonded to piezoelectric transducer. The application uniaxial strain leads large reorientation easy axis, which is detected by anisotropic magnetoresistance measurements. Calculations based on mean-field kinetic-exchange model provide microscopic understanding measured effect. reported smooth in-plane anisotropy, electrically induced magnetization switching, and detection unconventional crystalline components...