A5063898580- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Magnetic properties of thin films
- Ferroelectric and Piezoelectric Materials
- Theoretical and Computational Physics
- Spectroscopy and Quantum Chemical Studies
- Quantum and electron transport phenomena
- 2D Materials and Applications
- Mechanical and Optical Resonators
- Transition Metal Oxide Nanomaterials
- Magneto-Optical Properties and Applications
- Catalysis and Oxidation Reactions
- Geophysics and Sensor Technology
- Magnetism in coordination complexes
- Carbon Nanotubes in Composites
- Graphene research and applications
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- Magnetic Properties and Applications
- Inorganic Fluorides and Related Compounds
- Thermodynamic properties of mixtures
- Photoreceptor and optogenetics research
- Nonlinear Photonic Systems
University of Groningen
2016-2025
Los Alamos National Laboratory
2008
University of Cologne
2006-2007
Max Planck Institute for Solid State Research
2005
Budker Institute of Nuclear Physics
1996-1998
Zorginstituut Nederland
1994
It was recently observed that materials showing most striking multiferroic phenomena are frustrated spin-density-wave magnets. We present a simple phenomenological theory, which describes the orientation of induced electric polarization for various incommensurate magnetic states, its dependence on temperature and field, anomalies dielectric susceptibility at transitions. show can be domain walls vortices carry charge.
Abstract Multiply periodic states appear in a wide variety of physical contexts, such as the Rayleigh–Bénard convection, Faraday waves, liquid crystals and skyrmion recently observed chiral magnets. Here we study phase diagram an anisotropic frustrated magnet which contains five different multiply including crystal. We clarify mechanism for stabilization these discuss how they can be magnetic resonance electric polarization measurements. also find stable isolated skyrmions with topological...
We study the collective dynamics of Skyrmion crystal in thin films ferromagnetic metals resulting from nontrivial topology. It is shown that current-driven motion reduces topological Hall effect and trajectories bend away direction electric current (the effect). find a new dissipation mechanism noncollinear spin textures can lead to much faster relaxation than Gilbert damping, calculate dispersion phonons crystal, discuss effects impurity pinning Skyrmions.
The concept of toroidal moments in condensed-matter physics and their long-range ordering a so-called ferrotoroidic state is reviewed. We show that ferrotoroidicity as form primary ferroic order can be understood both from microscopic (multipole expansion) macroscopic (symmetry-based expansion the free energy) points view. definition local moment its transformation properties under space-inversion time reversal operations are highlighted extension to periodic bulk systems discussed....
It was recently realized that topological spin textures do not merely have mathematical beauty but can also give rise to unique functionalities of magnetic materials. An example is the skyrmion—a nano-sized bundle noncoplanar spins—that by virtue its nontrivial topology acts as a flux field on spin-polarized electrons. Lorentz transmission electron microscopy emerged powerful tool for direct visualization skyrmions in noncentrosymmetric helimagnets. Topologically, are equivalent bubbles...
The notion of non-trivial topological winding in condensed matter systems represents a major area present-day theoretical and experimental research. Magnetic materials offer versatile platform that is particularly amenable for the exploration spin solitons real space such as skyrmions. First identified non-centrosymmetric bulk materials, rapidly growing zoology hosting skyrmions related includes compounds, surfaces, thin films, heterostructures, nano-wires nano-dots. This underscores an...
Strongly correlated electron insulators are one of the most important classes materials in modern solid-state physics. We demonstrate that certain Mott insulators, usually geometrically frustrated, exhibit unexpected charge effects: for spin textures, spontaneous circular electric currents or nonuniform distribution exist ground state insulators. In addition, low-energy ``magnetic'' states contribute comparably to dielectric and magnetic response functions, ${ϵ}_{ik}(\ensuremath{\omega})$...
Electromagnon excitations in multiferroic orthorhombic RMnO3 are shown to result from the Heisenberg coupling between spins despite fact that static polarization arises much weaker Dzyaloshinskii-Moriya exchange interaction. We present a model incorporating structural characteristics of this family manganites is confirmed by far infrared transmission data as function temperature and magnetic field inelastic neutron scattering results. A deep connection found magnetoelectric dynamics spiral...
We study topological defects in anisotropic ferromagnets with competing interactions near the Lifshitz point. show that skyrmions and bi-merons are stable a large part of phase diagram. calculate skyrmion-skyrmion meron-meron attract each other form ring-shaped bound states zero magnetic field. At point merons carrying fractional charge become deconfined. These results imply unusual excitations may exist weakly frustrated magnets conventional crystal lattices.
Magnetic skyrmions are particle-like topological excitations recently discovered in chiral magnets. Their small size, protection and the ease with which they can be manipulated by electric currents generated much interest using for information storage processing. Recently, it was suggested that additional degrees of freedom exist magnetically frustrated materials. Here, we show dynamics antiskyrmions nanostripes magnets is strongly affected complex spin states formed at stripe edges. These...
Abstract The simultaneous presence of ferroelectricity and magnetism in multiferroics breaks both spatial inversion time reversal symmetries at the macroscopic scale, which opens door to many interesting phenomena resembles violation these particle physics. symmetry breaking occurs spontaneously phase transitions rather than level fundamental interactions, thus can be controlled. Moreover, each crystal is a universe itself with unique set symmetries, coupling constants ordered patterns,...
We give general arguments that show the linear magnetoelectric effect in antiferromagnetic materials gives rise to a magnetocapacitance anomaly---a divergence of dielectric constant at magnetic ordering temperature ${T}_{N}$ appears an applied field. The measurement magnetodielectric response thus provides definitive and experimentally accessible method recognize materials, circumventing experimental difficulties often involved measuring electric polarization. confirm this result using...
We show that nonrelativistic exchange interactions and spin fluctuations can give rise to a linear magnetoelectric effect in collinear antiferromagnets at elevated temperatures exceed relativistic responses by more than 1 order of magnitude. how symmetry arguments, ab initio methods, Monte Carlo simulations be combined calculate temperature-dependent susceptibilities entirely from first principles. The application our method Cr2O3 gives quantitative agreement with experiment.
The lack of inversion symmetry in the crystal lattice magnetic materials gives rise to complex noncollinear spin orders through interactions a relativistic nature, resulting interesting physical phenomena, such as emergent electromagnetism. Studies cubic chiral magnets revealed universal phase diagram composed helical spiral, conical and skyrmion phases. We report remarkable deviation from this behavior. By combining neutron diffraction with magnetization measurements, we observe new...
Abstract Magnetic skyrmions are topologically protected nanoscale spin textures with particle-like properties. In bulk cubic helimagnets, they appear under applied magnetic fields and condense spontaneously into a lattice in narrow region of the phase diagram just below ordering temperature, so-called A-phase. Theory, however, predicts to be locally stable wide range temperatures. Our neutron diffraction measurements reveal formation skyrmion states large areas diagram, from lowest...
Orbital ordering occurs in many transition metal compounds with Jahn–Teller ions (Cu2+, Mn3+, low-spin Ni3+, Ti3+ etc). It plays an important role these materials. At the same time, exchange interactions orbitally degenerate systems are inherently frustrated, even materials simple crystal lattices. We discuss origin of this frustration, considering detail cubic and triangular lattices ions. also possible types ground states such systems, e.g., disordered orbital liquids due to...