A5090253714- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Magnetic Properties and Synthesis of Ferrites
- Magnetic properties of thin films
- Magneto-Optical Properties and Applications
- 2D Materials and Applications
- Solid-state spectroscopy and crystallography
- Crystal Structures and Properties
- Perovskite Materials and Applications
- Ferroelectric and Piezoelectric Materials
- Metamaterials and Metasurfaces Applications
- Magnetic Properties and Applications
- Quantum and electron transport phenomena
- Heusler alloys: electronic and magnetic properties
- Electronic and Structural Properties of Oxides
- Quantum Mechanics and Non-Hermitian Physics
- Magnetism in coordination complexes
- Malaria Research and Control
- Rare-earth and actinide compounds
- Organic and Molecular Conductors Research
- Optical Polarization and Ellipsometry
- Analytical chemistry methods development
Leibniz Institute for Solid State and Materials Research
2020-2025
RIKEN Center for Emergent Matter Science
2014-2024
Budapest University of Technology and Economics
2012-2020
Hungarian Academy of Sciences
2012-2017
Abstract The Weyl semimetal (WSM), which hosts pairs of points and accompanying Berry curvature in momentum space near Fermi level, is expected to exhibit novel electromagnetic phenomena. Although the large optical/electronic responses such as nonlinear optical effects intrinsic anomalous Hall effect (AHE) have recently been demonstrated indeed, conclusive evidence for their topological origins has remained elusive. Here, we report gigantic magneto-optical (MO) response arising from...
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 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 proposals suggest that 3$d$ transition-metal systems such as Na${}_{2}$Co${}_{2}$TeO${}_{6}$, in which the cobalt ions form honeycomb lattice sheets, may feature significant Kitaev interaction spite of nominally weak spin-orbit coupling and thus become candidates for realizing a spin liquid (KSL). The authors present data on thermal conductivity Na${}_{2}$Co${}_{2}$TeO${}_{6}$ show field-temperature phase diagram strongly resembles iconic prime KSL candidate material...
Orbital degrees of freedom mediating an interaction between spin and lattice were predicted to raise strong magnetoelectric effect, i.e., realize efficient coupling magnetic ferroelectric orders. However, the effect orbital fluctuations has been considered only in a few materials, as orbital-degeneracy driven Jahn-Teller rarely couples polarization. Here, we explore spin-lattice multiferroic Swedenborgites with mixed valence active transition metal ions on stacked triangular Kagome using...
Abstract The report of a half-quantized thermal Hall effect and oscillatory structures in the magnetothermal conductivity Kitaev material α -RuCl 3 have sparked strong debate on whether it is generated by Majorana fermion edge currents, spinon Fermi surface, or other more conventional mechanisms are at its origin. Here, we low temperature ( κ ) another candidate material, Na 2 Co TeO 6 . application magnetic field B along different principal axes crystal reveals directional-dependent impact...
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...
The ultimate goal of multiferroic research is the development new-generation non-volatile memory devices, so-called magnetoelectric (ME) memories, where magnetic bits are controlled via electric fields without application electrical currents subject to dissipation. This low-power operation exploits entanglement magnetization and polarization coexisting in materials. Here we demonstrate optical readout ME states antiferromagnetic (AFM) antiferroelectric (AFE) LiCoPO$_4$, based on strong...
Y-type hexaferrites are one of the most promising multiferroic materials for applications that allow electric field control magnetization near room temperature. Here, authors systematically investigate stability competing magnetic and phases several hexaferrite single crystals by performing magnetization, polarization, neutron diffraction measurements. They also study magnetization-polarization coupling simultaneously applying fields, reveal how it changes as a function
High-resolution thermal expansion and magnetostriction measurements were performed on single crystals of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{RuCl}}_{3}$ in magnetic fields applied parallel to the Ru-Ru bonds. The length changes measured direction perpendicular honeycomb planes. Our data show clear thermodynamic characteristics for field-induced phase transition at critical field ${\ensuremath{\mu}}_{0}{H}_{\mathrm{c}1}=7.8(2)\phantom{\rule{0.16em}{0ex}}\mathrm{T}$ where...
In this combined theoretical and experimental research, the authors investigate anisotropic magnetic magnetoelastic properties of quantum spin-liquid candidate $\ensuremath{\alpha}$-RuCl${}_{3}$. They find that magnetostriction anisotropy is unusually large compared to magnetization, which they relate strong \ensuremath{\Gamma}'-type coupling. also observe nonsymmetric for fields canted out honeycomb plane in opposite directions, relative orientation field with respect RuCl${}_{6}$ octahedra.
The resistance of a heavy metal can be modulated by an adjacent magnetic material through the combined effects spin Hall effect, inverse and dissipation accumulation at interface. This phenomenon is known as magnetoresistance. occur via various mechanisms, with spin-transfer torque being most extensively studied. In this work, we report observation magnetoresistance interface between platinum insulating altermagnetic candidate, Ba$_2$CoGe$_2$O$_7$. Our findings reveal that heterostructure...
Centrosymmetric compounds which host three-dimensional topological spin structures comprise a distinct subclass of materials in multiple-<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi mathvariant="bold">q</a:mi></a:mrow></a:math> magnetic order is stabilized by anisotropy and bond frustration contrast to the more common path antisymmetric exchange interactions. Here we investigate static dynamic properties cubic perovskite <d:math...
Layered van der Waals tellurides reveal topologically nontrivial properties that give rise to unconventional magneto-transport phenomena. Additionally, their semimetallic character with high mobility makes them promising candidates for large magneto-thermoelectric effects. Remarkable studies on the very and Nernst effect in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>WTe</a:mi><a:mn>2</a:mn></a:msub></a:math> have been reported, raising questions about whether this...
We derive a sum rule to demonstrate that the static magnetoelectric (ME) effect is governed by optical transitions are simultaneously excited electric and magnetic components of light. The ME applicable broad class materials lacking spatial inversion time-reversal symmetries, including multiferroic compounds. Due dynamical effect, excitations in these can exhibit directional dichroism, i.e., absorption coefficient be different for counter-propagating light beams. According rule, magnitude...
Spin excitations were studied by absorption spectroscopy in CaBaCo4O7 which is a type-I multiferroic compound with the largest magnetic-order induced ferroelectric polarization ({\Delta}P=17mC/m2) reported, so far. We observed two optical magnon branches: solely electric dipole allowed one and mixed magnetoelectric resonance. The entangled magnetization dynamics of resonance gives rise to unidirectional light absorption, i.e. that mode absorbs electromagnetic radiation for propagation...
Abstract Mutual control of the electricity and magnetism in terms magnetic ( H ) electric E fields, magnetoelectric (ME) effect, offers versatile low power consumption alternatives to current data storage, logic gate, spintronic devices. Despite its importance, -field over magnetization M with significant magnitude was observed only at temperatures. Here we have successfully stabilized a simultaneously ferrimagnetic ferroelectric phase Y-type hexaferrite single crystal up 450 K, demonstrated...
Magnetic frustration in a material may drive spin-spiral order, spontaneously breaking the translation and chiral symmetries of crystal. The underlying hierarchy magnetic interactions is reflected magnon excitations, which can be probed by inelastic neutron scattering. Here, authors study dispersions magnons helimagnet FeP compare experimentally observed spectra with simulations. Upon examination alternative models, are able to correctly describe spin excitations unveil corresponding mechanism.
Competing exchange interactions can produce complex magnetic states together with spin-induced electric polarizations. With competing on alternating triangular and kagome layers, the swedenborgite ${\mathrm{CaBaCo}}_{4}{\mathrm{O}}_{7}$ may have one of largest measured polarizations $\ensuremath{\sim}1700$ nC/${\mathrm{cm}}^{2}$ below its ferrimagnetic transition temperature at 70 K. Upon rotating our sample about $\mathbf{c}=[0,0,1]$ while field is fixed along $[1,0,0]$, threefold splitting...
We have demonstrated that spin-driven ferroelectricity in a tetragonal multiferroic Ba(2)CoGe(2)O(7) is controlled by applying uniaxial stress. found the application of compressive stress along [110] direction leads to 45° or 135° rotation sublattice magnetization staggered antiferromagnetic order this system. This allows spontaneous electric polarization appear c axis. The present study suggests an anisotropic stress, which simplest way control symmetry matter, can induce variety...
The magnetic phase diagram of a polar ferrimagnet ${\mathrm{CaBaFe}}_{4}{\mathrm{O}}_{7}$ with easy axis has been investigated by measurements magnetization, specific heat, and magnetoelectricity. A ferrimagnetic transition takes place at ${T}_{\mathrm{C}1}=275$ K within the orthorhombic followed second ${T}_{\mathrm{C}2}=211$ K. Below ${T}_{\mathrm{C}2}$, successive metamagnetic transitions occur for fields applied perpendicular to axis, implying sequential emergence states which are...