I. G. Bostrem

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 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

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

-fluctuations but the longitudinal

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

theta

Hidden Galilean symmetry, conservation laws and emergence of spin current in the soliton sector of chiral helimagnet

-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.

Bose?Einstein condensation of semi-hard bosons in the S = 1 dimerized organic compound F2PNNNO

We show that the bulk transport magnetic current is generated by the moving magnetic kink crystal (chiral soliton lattice) formed in the chiral helimagnet under the static magnetic field applied perpendicular to the helical axis. The current is caused by the non-equilibrium transport momentum with the kink mass being determined by the spin fluctuations around the kink crystal state. An emergence of the transport magnetic currents is then a consequence of the dynamical off-diagonal long range order along the helical axis. We derive an explicit formula for the inertial mass of the kink crystal and the current in the weak field limit. PACS numbers: Valid PACS appear here How to create, transport, and manipulate spin currents is a central problem in the multidisciplinary field of spintronics. 1 The key theoretical concepts there include the current-driven spin-transfer torque 2 and resultant force acting on a domain wall (DW) 3 in metallic ferromagnetic/nonmagnetic multilayers, the dissipationless spin currents in paramagnetic spin-orbit coupled systems, 4 and magnon transport in textured magnetic structures. 5 A fundamental query behind the issue is how to describe transport magnetic currents. 6 Conventionally, the charge current is defined by the product of the carrier density and the drift velocity related via the continuity equation. In the case of spin current, the deviation of the spin projection from its equilibrium value plays a role of a charge. Then, an emergence of the transport magnetic currents may be expected in non-equilibrium state as a manifestation of the dynamical off-diagonal long range

Spiral vortices in a two-dimensional ferromagnet

We demonstrated that the chiral soliton lattice formed out of a chiral helimagnet exhibits coherent sliding motion by applying a time-dependent magnetic field parallel to the helical axis, in addition to a static field perpendicular to the helical axis. To describe the coherent sliding, we use the collective coordinate method and numerical analysis. We also show that the time-dependent sliding velocity causes a time-varying Berry cap which causes the spin-motive-force. A salient feature of the chiral soliton lattice is appearance of the strongly amplified spin motive force which is directly proportional to the macroscopic number of solitons (magnetic kinks).

Chapter 10 Magnetic properties of low-dimensional organic crystals of the PNNNO family

We present a quantum cluster solver for the spin-S Heisenberg model on a two-dimensional lattice. The formalism is based on the real-space renormalization procedure and uses the lattice point group-theoretical analysis and non-Abelian SU(2) spin symmetry technique. The exact diagonalization procedure is used twice at each renormalization group step. The method is applied to the spin-half antiferromagnet on a square lattice, and a calculation of local observables is demonstrated. A symmetry-based truncation procedure is suggested and verified numerically.

Topological magnetization jumps in a confined chiral soliton lattice

Abstract An appearance of the transport spin current in chiral helimagnet is mathematically justified based on the symmetry arguments. Although the starting Lagrangian of the chiral magnet with the Berry phase term and the parity-violating Dzyaloshinskii–Morya coupling is not manifestly Galilean invariant, the Lie point group symmetry analysis and the variational symmetry analysis elucidate the hidden Galilean symmetry and the existence of the linear momentum as a conserved Noether current, respectively.