A5013460301- Magnetic properties of thin films
- Heusler alloys: electronic and magnetic properties
- Magneto-Optical Properties and Applications
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- MXene and MAX Phase Materials
- Magnetic Properties and Applications
- ZnO doping and properties
- Magnetic and transport properties of perovskites and related materials
- Photonic and Optical Devices
- Multiferroics and related materials
- Surface and Thin Film Phenomena
- Advanced Memory and Neural Computing
- 2D Materials and Applications
- Photonic Crystals and Applications
- Topological Materials and Phenomena
- Chalcogenide Semiconductor Thin Films
- Copper Interconnects and Reliability
- Characterization and Applications of Magnetic Nanoparticles
- Semiconductor materials and interfaces
- Magnetic Properties and Synthesis of Ferrites
- Spectroscopy and Quantum Chemical Studies
- Optical Coatings and Gratings
- Phase-change materials and chalcogenides
- Photorefractive and Nonlinear Optics
Charles University
2002-2024
Czech Academy of Sciences, Institute of Physics
2001-2024
Czech Academy of Sciences
2023
VSB - Technical University of Ostrava
2010-2020
University of Kaiserslautern
2006-2013
Japan Science and Technology Agency
2004-2006
RIKEN
2004-2006
RIKEN Center for Emergent Matter Science
2005
Centre National de la Recherche Scientifique
2001-2005
Université Paris-Sud
2003-2005
Abstract Magneto-optical (MO) effects, viz. magnetically induced changes in light intensity or polarization upon reflection from transmission through a magnetic sample, were discovered over century and half ago. Initially they played crucially relevant role unveiling the fundamentals of electromagnetism quantum mechanics. A more broad-based relevance wide-spread use MO methods, however, remained quite limited until 1960s due to lack suitable, reliable easy-to-operate sources. The advent...
Cobalt-based full-Heusler compounds with composition Co2M ′ Z (where M is a transition metal and main group element) are attracting attention due to their predicted half-metallic behaviour, considerably desired property for spin-dependent electron transport devices.Knowledge of the basic magnetic properties these materials, in particular form thin films, required both fully exploit promising understand underlying electronic structure establish structure-property relationships.In this Topical...
We demonstrate the method to calculate spatial distributions of spin current and accumulation in multiterminal ferromagnetic/nonmagnetic hybrid structure using an approximate electrotransmission line. The analyses based on obtained equation yield results, good agreement with experimental ones. This implies that allows us determine diffusion length additionally connected electrically floating wire from reduction signal.
We have performed nonlocal spin injection into a nanoscale ferromagnetic particle configured in lateral spin-valve structure to switch its magnetization only by current. The aligns the of parallel injector. current responsible for switching is estimated from experiment be about 200 microA, which reasonable compared with values obtained conventional pillar structures. Interestingly, always occurs antiparallel particle-injector magnetic configurations, where no opposite observed. Possible...
Co$_2$FeSi(100) films with L2$_1$ structure deposited onto MgO(100) were studied exploiting both longitudinal (LMOKE) and quadratic (QMOKE) magneto-optical Kerr effect. The exhibit a huge QMOKE signal maximum contribution of up to 30 mdeg, which is the largest in reflection that has been measured thus far. This large value fingerprint an exceptionally spin-orbit coupling second or higher order. rather coercivity 350 70 Oe for film thicknesses 22 98 nm, respectively. Despite fact are...
We report the detection of clear spin-valve signal without any spurious magnetoresistive in a lateral structure consisting Cu∕Ni−Fe ohmic junction using local current injection. The obtained is much larger than that nonlocal configuration because efficient spin accumulation. injection experiments with different probe configurations proved caused by spin-dependent boundary resistance at interface between ferromagnetic voltage and spin-polarized nonmagnetic wire.
We report on the influence of improved L21 ordering degree magnetic properties Co2MnSi Heusler films. Different fractions phase are obtained by different postgrowth annealing temperatures ranging from 350 °C to 500 °C. Room temperature magneto-optical Kerr effect measurements reveal an increase coercivity at intermediate 425 This is probably a result increasing number pinning centers one hand and drop cubic anisotropy constant K1 factor 10 other for amount phase. Furthermore, Brillouin light...
The Heusler compound CoTiSb was synthesized and investigated theoretically experimentally with respect to electronic structure optical, mechanical, vibrational properties. optical properties were in a wide spectral range from 10 meV 6.5 eV compared ab initio calculations. spectra confirm the semiconducting nature of CoTiSb, strong exciton absorption at 1.83 eV. calculated phonon dispersion as well elastic constants verify mechanical stability cubic $C{1}_{b}$ system. Furthermore, solid...
A series of Al and MgO-capped Co${}_{2}$FeAl${}_{0.5}$Si${}_{0.5}$ epitaxial thin films grown on MgO with various levels L2${}_{1}$ ordering was obtained by in situ annealing. The were studied means x-ray absorption spectroscopy, magnetic circular dichroism (XMCD), magneto-optical Kerr effect magnetometry, Brillouin light scattering. We find the anisotropy constants decrease, while spin wave stiffness increases as samples are annealed to higher temperatures. magnetization determined...
A rigorous theory of radiation from dipoles embedded inside an arbitrary multilayer system is presented. In particular, we derive explicit expressions for the angular distribution electromagnetic field and intensity radiated by dipole into surrounding media. Under assumptions mutual incoherence calculations are extended to a layer radiating dipoles. Special configurations corresponding (i) single near dielectric interface, (ii) surrounded semi-infinite media, (iii) placed on top waveguide...
How does one determine the magnetization state and hysteresis loop corresponding to of ferromagnetic (FM) layers located at a given depth in stack FM/non-FM by means magneto-optical Kerr effect? For this purpose representation effect complex rotation-ellipticity plane is introduced. A sensitivity function controlling defined its dependence on photon energy angle incidence studied. general way in-depth location FM layer, from which signal originates, proposed. In case bilayer structure,...
The junction size dependence of the spin accumulation in a nonmagnet is studied by using lateral valves geometry consisting Py/Cu ohmic junctions. We experimentally demonstrate that reducing drastically improves efficiency injection into Cu wire because enhancement resistance for Py wire. polarization increases exponentially with area irrespective same spacing between injector and detector. signal yields diffusion lengths which are reasonable values compared previous experiments.
Brillouin light scattering spectroscopy from so-called standing spin waves in thin magnetic films is often used to determine the exchange constant. The data analysis of experimentally determined spin-wave modes requires an unambiguous assignment correct mode orders. Often additional investigations are needed guarantee assignment. This particularly important case Heusler compounds where values constant vary substantially between different compounds. As a showcase, we report on determination...
Magnetic linear dichroism and birefringence in (Ga,Mn)As epitaxial layers is investigated by measuring the polarization plane rotation of reflected linearly polarized light when magnetization lies sample. We report on spectral dependence ellipticity angles a broad energy range $0.12--2.7\phantom{\rule{4pt}{0ex}}\mathrm{eV}$ for series optimized samples covering wide Mn dopings Curie temperatures find clear blueshift dominant peak at exceeding host material band gap. These results are...
We have investigated the exchange constant A (exchange stiffness D) and magnetic anisotropy of Co2MnAlxSi1−x (CMAS) Heusler compounds as a function film composition. In case Co2MnSi, was found to be 23.5 pJ/m (D=5.86 meV nm2). Furthermore, decreased with an increase in Al content x. Co2MnAl, it 4.8 (D=1.90 Finally, cubic K1 CMAS films small (below 10 kJ/m3) did not exhibit simple dependence on
The spin-wave relaxation mechanisms after intense laser excitation in ferromagnetic nickel films are investigated with all-optical pump-probe experiments. Uniform precession (Kittel mode), Damon-Eshbach surface modes and perpendicular standing spin waves can be identified by their dispersion f(H). However, different to other ferromagnets f(H) deviates from the expected behavior. Namely, a mode discontinuity is observed, that attributed non-linear process. Above critical field power spectrum...
Using Brillouin light scattering spectroscopy, we determine the spin-wave exchange stiffness D and constant A for thin films of full Heusler compound Co2FeSi prepared by pulsed laser deposition. The thermal spectra were measured in various magnetic fields, different transferred momenta, film thicknesses. Fitting observed frequencies, find an extraordinarily large value = 7.15 ± 0.20 meV nm2 (A 31.5 1.0 pJ m−1) which is, to best our knowledge, only surpassed intermetallic Fe53Co47 (Liu et al...
A new combination of different vectorial magnetometry techniques using magnetooptic Kerr effect is described. The processing the experimental data contains separation linear and quadratic parts magnetization curves determination all three components vector in units rotation without any normalization to saturation values. procedure includes measurements with parallel perpendicular polarized incident light an external magnetic field plane incidence light. complex amplitude theoretic...
Full Heusler Co2TiSn thin film were grown by DC magnetron sputtering on MgO(001) substrates at temperatures from ambient up to 800°C. The epitaxial films with full structure and high purity achieved 700°C thickness ranging ~ 20 nm over 1000 enabling deeper study of the growth effect properties. state was investigated wide range techniques including atomic force electron microscopy, X-ray diffraction photoelectron spectroscopy, magnetometry, magnetooptical ellipsometry supported ab initio...
In most studies utilizing the magneto-optic Kerr effect (MOKE), detected change of polarized light upon reflection from a magnetized sample is supposed to be proportional magnetization $\mathbf{M}$. However, MOKE signatures quadratic in $\mathbf{M}$ have also been identified and utilized, e.g., sense structural order Heusler compounds, detect spin-orbit torque or image antiferromagnetic domains. our study, we observe strong anisotropic contribution third $\mathrm{Ni}$(111) thin films,...
We have investigated experimentally the nonlocal voltage signal (NLVS) in lateral Permalloy $(\mathrm{Py})∕\mathrm{Cu}∕\mathrm{Py}$ spin-valve devices with different width of Cu stripes. found that NLVS strongly depends on distribution spin-polarized current inside strip vicinity Py detector. To explain these data we developed a diffusion model describing spatial (three dimensional) device. The results our calculations show is decreased by factor 10 due to spin flip scattering occurring at...
Tetragonal phase of CuMnAs progressively appears as one the key materials for antiferromagnetic spintronics due to efficient current-induced spin-orbit torques whose existence can be directly inferred from crystal symmetry. Theoretical understanding spintronic phenomena in this material, however, relies on detailed knowledge electronic structure (band and corresponding wave functions) which has so far been tested only a limited extent. We show that AC permittivity (obtained ellipsometry) UV...