相关论文: Multiple Helical Spin Density Waves and Magnetic S…
Multiple spin density waves and related vortex-type magnetic structures in the itinerant electron system with inversion symmetry have been investigated on the basis of the Hubbard model and the generalized Hartree-Fock approximation…
Analytic properties of the multiple spin density waves showing vortex structures, which have recently been found in the fcc Hubbard model using the generalized Hartree-Fock (GHF) approximation, have been investigated. It is shown that the…
A theory of Kondo lattices is applied to studying possible magnetic and charge structures of itinerant-electron antiferromagnets. Even helical spin structures can be stabilized when the nesting of the Fermi surface is not sharp and the…
The relative stability among the multiple spin density wave (MSDW) states in fcc transition metals has been investigated on the basis of a Ginzburg-Landau type of free energy with terms up to the fourth order in magnetic moments. Obtained…
We consider fermions in one-dimensional superlattices (SL's), modeled by site-dependent Hubbard-U couplings arranged in a repeated pattern of repulsive (i.e., U>0) and free (U=0) sites. Density Matrix Renormalization Group (DMRG)…
Ground state and spin-wave spectrum of cubic magnets with the Dzyaloshinskii-Moriya interaction (DMI) such as MnSi and FeGe are studied theoretically. The linear spin-wave theory is developed. The spin-wave spectrum depends strongly on the…
This work studies the resonance excitations of the three-dimensional skyrmions lattice in the finite thickness plate of an isotropic chiral magnet using spin dynamics simulations. We found that the absorption spectra and resonance modes…
We explore the interplay between topology and eigenmodes by changing the stabilizing mechanism of skyrmion lattices (skX). We focus on two prototypical ultrathin films hosting an hexagonal (Pd/Fe/Ir(111)) and a square (Fe/Ir(111)) skyrmion…
We study the zero-temperature spin fluctuations of a two-dimensional itinerant-electron system with an incommensurate magnetic ground state described by a single-band Hubbard Hamiltonian. We introduce the (broken-symmetry) magnetic phase at…
Magnetic skyrmions were thought to be stabilised only in inversion-symmetry breaking structures, but skyrmion lattices were recently discovered in inversion symmetric Gd-based compounds, spurring questions of the stabilisationmechanism. A…
We introduce a novel approach for the investigation of spin-wave excitations in itinerant ferromagnets. Our theory is based on a variational treatment of general multi-band Hubbard models which describe elements and compounds of transition…
We consider electrons on a honeycomb or triangular lattice doped to the saddle point of the bandstructure. We assume system parameters are such that spin density wave (SDW) order emerges below a temperature $T_N$ and investigate the nature…
The ground states of the two-dimensional repulsive Hubbard model are studied within the unrestricted Hartree-Fock (UHF) theory. Magnetic and charge properties are determined by systematic, large-scale, exact numerical calculations, and…
The microscopic basis for the stability of itinerant ferromagnetism in correlated electron systems is examined. To this end several routes to ferromagnetism are explored, using both rigorous methods valid in arbitrary spatial dimensions, as…
In this work we analyze the instability conditions for spin-density-waves (SDW) formation on the surface of strong topological insulators. We find that for a certain range of Fermi-energies and strength of interactions the SDW state is…
The helimagnet (HM) and skyrmion lattice (SL) are topologically nontrivial magnetic states. Their spin texture gives rise to finite topological magnetic field and Lorentz force. As a demonstration of the emergent electrodynamics besides the…
This thesis investigates the magnetic, spectral, and transport properties of strongly correlated electronic systems, with a primary focus on the Hubbard model and its extensions relevant for real materials. Within the dynamical mean-field…
Very often the skyrmions form a triangular crystal in chiral magnets. Here we study the effect of itinerant electrons on the structure of skyrmion crystal (SkX) on triangular lattice using Kondo lattice model in the large coupling limit and…
Recent theoretical studies have demonstrated the possibility to excite and sustain noncollinear magnetization states in ferromagnetic nanowires. The resulting state is referred to as a spin-density wave (SDW). SDWs can be interpreted as…
We present an isotropic spin wave (ISW) theory of short-range order in Heisenberg magnets, and apply it to square lattice S=1/2 and S=1 antiferromagnets. Our theory has three identical (isotropic) spin wave modes, whereas the conventional…