Chain In External Magnetic Field Research Articles

Exact intrinsic localized excitation of an anisotropic ferromagnetic spin chain in external magnetic field with Gilbert damping, spin current and [formula omitted]-symmetry

We obtain the exact one-spin intrinsic localized excitation in an anisotropic Heisenberg ferromagnetic spin chain in a constant/variable external magnetic field with Gilbert damping included. We also point out how an appropriate magnitude spin current term in a spin transfer nano-oscillator (STNO) can stabilize the tendency towards damping. Further, we show how this excitation can be sustained in a recently suggested PT-symmetric magnetic nanostructure. We also briefly consider more general spin excitations.

Frustrated spin-1/2 ladder with ferro- and antiferromagnetic legs

Two-leg spin-1/2 ladder systems consisting of a ferromagnetic leg and an antiferromagnetic leg are considered where the spins on the legs interact through antiferromagnetic rung couplings J1. These ladders can have two geometrical arrangements either zigzag or normal ladder and these systems are frustrated irrespective of their geometry. This frustration gives rise to incommensurate spin density wave, dimer and spin fluid phases in the ground state. The magnetization in the systems decreases linearly with J12, and the systems show an incommensurate phase for 0.0<J1<1.0. The spin-spin correlation functions in the incommensurate phase follow power law decay which is very similar to Heisenberg antiferromagnetic chain in external magnetic field. In large J1 limit, the normal ladder behaves like a collection of singlet dimers, whereas the zigzag ladder behaves as a one dimensional spin-1/2 antiferromagnetic chain.

A simple method of complex ferrimagnetic properties description of AB 1AB 2-superlattice structures with a strong perpendicular anisotropy contribution (Blume–Capel model)

We have studied the ferrimagnetic spin-1 AB 1AB 2 superlattice in the presence of perpendicular single-ion anisotropy (Blume–Capel model) to have a direct evidence of the existence of multicompensation and tricritical effects. We present the theory based on the use of the exact solution for spin-1 Ising linear chain in external magnetic field. The free energy is calculated from the Bogolyubov's variational principle in frame of the transfer matrix method. Then, we obtain the description of the second as well as first-order phase transition, together with the layered and total magnetization curves. Our results (phase diagrams) indicate the possible existence of 1–3-compensation point effects for particular values of magnetic structure parameters. Mainly, the contribution of the perpendicular single-ion anisotropy is verified.

A proposal to include damping effects in the spectral density approach

Recently there has been proposed a modification of the spectral density method (SDM) to take into account damping effects for Fermi systems. There are in any case some difficulties concerning Bose and classical systems. The authors suggest a simple way of avoiding such difficulties and preserving the earliest idea for discussing damping effects. A classical ferromagnetic linear chain in external magnetic field is studied.