A. S. Ovchinnikov

Magnetic phase transitions in optical spectrum of magnetic semiconductor CuO

Abstract The absorption coefficient in the region of a wide charge-transfer band (3.19xa0eV) in CuO exhibits anomalously large, up to 8%, changes near two magnetic phase transition temperatures. It can be used for the optical detection of magnetic phase transitions.

Magnetic hysteresis and domain wall dynamics in single chain magnets with antiferromagnetic interchain coupling.

Using Monte Carlo simulations we investigate magnetic hysteresis in two- and three-dimensional systems of weakly antiferromagnetically coupled spin chains based on a scenario of domain wall (kink) motion within the chains. By adapting the model of walkers to simulate the domain wall dynamics and using the Ising-like dipole-dipole model, we study the effects of interchain coupling, temperature and anisotropy axis direction on hysteresis curves.

Magnetic soliton transport over topological spin texture in chiral helimagnet with strong easy-plane anisotropy

We show the existence of an isolated soliton excitation over the topological ground-state configuration in chiral helimagnet with the Dzyaloshinskii-Moryia exchange and the strong easy-plane anisotropy. The magnetic field perpendicular to the helical axis stabilizes the kink crystal state which plays a role of topological protectorate for the traveling soliton with a definite handedness. To find new soliton solution, we use the Baecklund transformation technique. It is pointed out that the traveling soliton carries the magnon density and a magnetic soliton transport may be realized.

Theory of spin resonance in a chiral helimagnet

It is suggested that marked features of symmetry breaking mechanism and elementary excitations in chiral helimagnet come up as visible effects in electron spin resonance (ESR) profile. Under the magnetic field applied parallel and perpendicular to the helical axis, elementary excitations are respectively described by the helimagnon associated with rotational symmetry breaking and the magnetic kink crystal phonon associated with translational symmetry breaking. We demonstrate how the ESR spectra distinguish these excitations.

Magnetic hysteresis in a molecular Ising ferrimagnet: Glauber dynamics approach

Motivated by recent experimental results reporting giant coercive fields in Co(II)-based molecular magnets we present a theory of hysteresis phenomena based on the Glauber stochastic dynamics. Unusual form of hysteresis loops is similar to those of found in Co-based quasi-one-dimensional ferrimagnet CoPhOMe at low temperatures. Temperature dependence of the coercive field has a characteristic form with an inflection that may serve as an indicator of the Glauber dynamics in real compounds. A relevance of the model for other Co-based molecular magnets is discussed.

Theory of spin current in chiral helimagnets

We give detailed description of the transport spin current in the chiral helimagnet. Under the static magnetic field applied perpendicular to the helical axis, the magnetic kink crystal (chiral soliton lattice) is formed. Once the kink crystal begins to move under the Galilean boost, the spin-density accumulation occurs inside each kink and there emerges periodic arrays of the induced magnetic dipoles carrying the transport spin current. The coherent motion of the kink crystal dynamically generates the spontaneous demagnetization field. This mechanism is analogous to the D{o}ring-Becker-Kittel mechanism of the domain wall motion in ferromagnets. To describe the kink crystal motion, we took account of not only the tangential

Transport spin current driven by the moving kink crystal in a chiral helimagnet

phi

Low-energy excitations and thermodynamical properties of the quantum (5/2, 1/2, 1/2) ferrimagnetic chain

-fluctuations but the longitudinal

Coherent sliding dynamics and spin motive force driven by crossed magnetic fields in a chiral helimagnet

theta

Symmetry adapted finite-cluster solver for quantum Heisenberg model in two dimensions: a real-space renormalization approach

-fluctuations around the helimagnetic configuration. Based on the collective coordinate method and the Diracs canonical formulation for the singular Lagrangian system, we derived the closed formulae for the mass, spin current and induced magnetic dipole moment accompanied with the kink crystal motion. To materialize the theoretical model presented here, symmetry-adapted material synthesis would be required, where the interplay of crystallographic and magnetic chirality plays a key role there.