A5071117405- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Magnetic and transport properties of perovskites and related materials
- Magnetic properties of thin films
- Physics of Superconductivity and Magnetism
- Malaria Research and Control
- Mosquito-borne diseases and control
- Ferroelectric and Piezoelectric Materials
- Topological Materials and Phenomena
- Crystal Structures and Properties
- Electronic and Structural Properties of Oxides
- Magneto-Optical Properties and Applications
- Organic and Molecular Conductors Research
- Solid-state spectroscopy and crystallography
- Digital Imaging for Blood Diseases
- Quantum and electron transport phenomena
- Magnetism in coordination complexes
- Magnetic Properties and Applications
- Optical Polarization and Ellipsometry
- Theoretical and Computational Physics
- Acoustic Wave Resonator Technologies
- Rare-earth and actinide compounds
- Inorganic Fluorides and Related Compounds
- Metamaterials and Metasurfaces Applications
- Characterization and Applications of Magnetic Nanoparticles
University of Augsburg
2016-2025
Budapest University of Technology and Economics
2013-2022
National Institute for Materials Science
2021
Institute for Physics
2021
University of Basel
2021
Lawrence Berkeley National Laboratory
2021
Norwegian University of Science and Technology
2021
Budapest University of Economics and Business
2020
Montavid Thermodynamic Research Group
2015-2017
Hungarian Academy of Sciences
2008-2014
We propose that concurrently magnetic and ferroelectric, i.e. multiferroic, compounds endowed with electrically-active excitations (electromagnons) provide a key to produce large directional dichroism for long wavelengths of light. By exploiting the control ferroelectric polarization magnetization in multiferroic oxide Ba$_2$CoGe$_2$O$_7$, we demonstrate realization such light-switch function at terahertz frequecies resonance electromagnon absorption. Our results imply this hidden potential...
Skyrmions are whirl-like topological spin objects with high potential for future magnetic data storage. A fundamental question that is relevant to both basic research and application whether ferroelectric (FE) polarization can be associated skyrmions' texture these manipulated by electric fields. We study the interplay between magnetism in lacunar spinel GaV4S8, which undergoes a structural transition orbital ordering at 44 K reveals complex phase diagram below 13 K, including ferromagnetic,...
Dynamical properties of the lattice structure were studied by optical spectroscopy in $A$Cr${}_{2}$O${}_{4}$ chromium spinel oxide magnetic semiconductors over a broad temperature region $T=10$--335 K. The systematic change $A$-site ions ($A=$ Mn, Fe, Co, Ni and Cu) showed that occupancy 3$d$ orbitals on $A$ site has strong impact dynamics. For compounds with orbital degeneracy (FeCr${}_{2}$O${}_{4}$, NiCr${}_{2}$O${}_{4}$, CuCr${}_{2}$O${}_{4}$), clear splitting infrared-active phonon modes...
The skyrmion lattice state (SkL), a crystal built of mesoscopic spin vortices, gains its stability via thermal fluctuations in all bulk host materials known to date. Therefore, existence is limited narrow temperature region below the paramagnetic state. This range can drastically increase systems with restricted geometries, such as thin films, interfaces and nanowires. Thermal quenching also promote SkL metastable over extended ranges. Here, we demonstrate more generally that proper choice...
Abstract Reversible ferroelectric domain wall movements beyond the 10 nm range associated with Rayleigh behavior are usually restricted to specific defect-engineered systems. Here, we demonstrate that such long-range naturally occur in improper ErMnO 3 during electric-field-cycling. We study electric-field-driven motion of walls, showing they readily return their initial position after having traveled distances exceeding 250 nm. By applying switching spectroscopy band-excitation...
We demonstrate that the onset of complex spin orders in ACr2O4 spinels with magnetic and Jahn-Teller active A=Fe Cu ions lowers lattice symmetry. This is clearly indicated by emergence anisotropic dynamics-i.e., pronounced phonon splittings-even when experiments probing static distortions fail. The crystal symmetry phase reduced from tetragonal to orthorhombic for both compounds. conical ordering FeCr2O4 also manifested hardening frequencies. In contrast, multiferroic CoCr2O4 no orbital...
The need to develop new methods for the high-sensitivity diagnosis of malaria has initiated a global activity in medical and interdisciplinary sciences. Most diverse variety emerging techniques are based on research-grade instruments, sophisticated reagent-based assays or rely expertise. Here, we suggest an alternative optical methodology with easy-to-use cost-effective instrumentation unique properties pigment reported previously determined quantitatively present study. Malaria pigment,...
Recent studies demonstrated the violation of reciprocity in optical processes low-symmetry magnetic crystals. In these crystals speed light can be different for counterpropagating beams. Correspondingly, they show strong directional anisotropies such as direction dependent absorption also called dichroism [Bord\'acs et al., Nat. Phys. 8, 734 (2012); Saito J. Soc. Jpn. 77, 013705 (2008)]. Based on symmetry considerations, we identify point groups materials which host and provide a list...
Multiferroics permit the magnetic control of electric polarization and magnetization. These static magnetoelectric (ME) effects are enormous interest: The ability to read write a state current-free by an voltage would provide huge technological advantage. Dynamic or optical ME equally interesting because they give rise unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, allow development diodes which...
We introduce a class of isolated magnetic skyrmions emerging within tilted ferromagnetic phases polar magnets with easy-plane anisotropy. The asymmetric structure these is associated an intricate pattern the energy density, which exhibits positive and negative asymptotics respect to surrounding state moment away from axis. Correspondingly, skyrmion-skyrmion interaction has anisotropic character can be either attractive or repulsive depending on relative orientation skyrmion pair. investigate...
We investigate the stability of N\'eel skyrmions against tilted magnetic fields, in polar magnets with uniaxial anisotropy ranging from easy-plane to easy-axis type. construct corresponding phase diagrams and internal structure skewed displaced cores. find that moderate increases range for fields along symmetry axis, while enhances their robustness fields. stress direction, which skyrmion cores are shifted, depends on underlying crystal lattice. The skyrmions, realized C$_{nv}$ symmetry,...
Abstract Magnetoelectric phenomena are intimately linked to relativistic effects and also require the material break spatial inversion symmetry time-reversal invariance. coupling can substantially affect light–matter interaction lead non-reciprocal light propagation. Here, we confirm on a fully experimental basis, without invoking either symmetry-based or material-specific assumptions, that optical magnetoelectric effect in materials with non-parallel magnetization ( M ) electric...
Magnetic skyrmions, vortex-like topological spin textures, have attracted much interest in a wide range of research fields from fundamental physics to spintronics applications. Recently, growing attention is also paid antiskyrmions emerging with opposite charge non-centrosymmetric magnets D2d or S4 symmetry. In these magnets, complex interplay among anisotropic Dzyaloshinskii-Moriya interaction, uniaxial magnetic anisotropy, and dipolar interactions generates various textures. However, the...
The metal-insulator transition has been investigated for pyrochlore molybdates R(2)Mo(2)O(7) with nonmagnetic rare-earth ions R. dynamical scaling analysis of ac susceptibility reveals that the geometrical frustration causes atomic spin-glass state. reentrant phase exists below ferromagnetic transition. electronic specific heat is enhanced as compared to band calculation result, perhaps due orbital fluctuation in half-metallic large rather reduced upon transition, likely because short-range...
We studied spin excitations in the magnetically ordered phase of noncentrosymmetric ${\mathrm{Ba}}_{2}{\mathrm{CoGe}}_{2}{\mathrm{O}}_{7}$ high magnetic fields up to 33 T. In electron resonance and far infrared absorption spectra we found several beyond two conventional magnon modes expected for such a two-sublattice antiferromagnet. show that multiboson spin-wave theory describes these unconventional modes, including spin-stretching characterized by an oscillating dipole quadrupole moment....
Broadband microwave spectroscopy has been performed on single-crystalline GaV$_4$S$_8$, which exhibits a complex magnetic phase diagram including cycloidal, N\'eel-type skyrmion lattice, as well field-polarized ferromagnetic phases below 13 K. At zero and small fields two collective modes are found at 5 15 GHz, characteristic of the cycloidal state in this easy-axis magnet. In finite fields, entering lattice phase, spectrum transforms into multi-mode pattern with absorption peaks near 4, 8,...
Abstract Magnetic anisotropy is anticipated to govern the formation of exotic spin textures reported recently in cubic chiral magnets, like low-temperature tilted conical and skyrmion lattice (SkL) states metastable SkLs with various geometry. Motivated by these findings, we quantified a series CoZnMn-type magnets. We found that strength highly enhanced towards low temperatures. Moreover, not only magnitude but also character drastically varies upon changing Co/Mn ratio. correlate changes...
We study the magneto-optical (MO) response of polar semiconductor BiTeI with giant bulk Rashba spin splitting at various carrier densities. Despite being nonmagnetic, material is found to yield a huge MO activity in infrared region under moderate magnetic fields (up 3 T). Our first-principles calculations show that enhanced comes mainly from intraband transitions between Rashba-split conduction bands. These connecting electronic states opposite directions become active due presence strong...
Improving the efficiency of malaria diagnosis is one main goals current research. We have recently developed a magneto-optical (MO) method which allows high-sensitivity detection pigment (hemozoin crystals) in blood via magnetically induced rotational motion hemozoin crystals. Here, we evaluate this MO technique for Plasmodium falciparum infected erythrocytes using in-vitro parasite cultures covering entire intraerythrocytic life cycle. Our novel detected densities as low ∼40 parasites per...
GaV$_4$S$_8$ is a multiferroic semiconductor hosting N{\'e}el-type magnetic skyrmions dressed with electric polarization. At T$_s$ = 42K, the compound undergoes structural phase transition of weakly first-order, from non-centrosymmetric cubic at high temperatures to polar rhombohedral structure low temperatures. Below T$_s$, ferroelectric domains are formed polarization pointing along any four $\left< 111 \right>$ axes. Although in this material size and shape ferroelectric-ferroelastic may...
We present a dielectric spectroscopy study of the polar dynamics linked to orbitally driven ferroelectric transition in Skyrmion host GaV(4)S(8). By combining THz and MHz-GHz techniques, we succeed detecting relaxational arising from coupled orbital fluctuations this material trace its temperature dependence paraelectric as well phase. The relaxation time significantly increases when approaching critical both sides transition. It is natural assume that these map at Jahn-Teller Because...
Abstract Improved methods for malaria diagnosis are urgently needed. Here, we evaluate a novel method named rotating-crystal magneto-optical detection (RMOD) in 956 suspected patients Papua New Guinea. RMOD tests can be conducted within minutes and at low cost. We systematically the capability of to detect infections by directly comparing it with expert light microscopy, rapid diagnostic polymerase chain reaction on capillary blood samples. show that compared exhibits 82% sensitivity 84%...