The spin-wave energy spectrum and transition temperature of the two-dimensional VSe2-like: A retarded Green's function method study.

Based on the recent discovery of intrinsic magnetism in monolayer films VSe2, we have constructed a two-dimensional (2D) Heisenberg model incorporating the 1T and 2H structures. These configurations consist of three layers: the upper and lower surface layers and a middle layer. Using the retarded Green's function method, we investigate the spin-wave energy spectrum, spin-wave density of states, and transition temperature of the system.

Skyrmion driven by rotary magnetic field on the surface of magnetic nanotube: a Monte Carlo study.

We report a Monte-Carlo simulation of the formation of skyrmions under a rotary magnetic field on a nanotube. The zero-field magnetic state is characterized as helical stripe domains swirling on the nanotube, with one to three periods depending on the ratio of Dzyaloshinskii-Moriya to ferromagnetic interaction and tubular size. Under a rotary magnetic field, the formation of skyrmions is in pair and the skyrmion number can be tuned.

Improvement and stabilization of exchange bias in ferromagnet/antiferromagnet/ferromagnet trilayers.

Exchange bias (EB) in ferromagnet/antiferromagnet bilayers, which has been extensively studied and applied for several decades, is sensitive to many factors such as layer thickness, texture and crystallization. Various factors in an antiferromagnet may counterbalance each other to limit and deteriorate EB. We used an unbiased Monte-Carlo method based on a modified Metropolis algorithm to predict that dependence of EB properties on antiferromagnetic anisotropy (K ) are highly improved by attaching a soft ferromagnet on the other side of the antiferromagnet.

Cooling-field dependence of dipole-induced loop bias.

In ferromagnet/antiferromagnet bilayers and core/shell nanoparticles, an exchange-bias-like loop bias phenomenon in the ferromagnet is observed solely due to the long-range dipolar interactions between ferromagnet and antiferromagnet. With increasing cooling field, the loop bias field may increase from zero in the bilayers or from a negative value in the core/shell nanoparticles to a positive saturated value, depending on the interfacial dipolar interaction and/or ferromagnetic/antiferromagnetic thickness. Using a modified Monte-Carlo method and the Meiklejohn-Bean model, the interfacial dipole fields (up to several teslas) and the domain sizes imprinted on the interfacial antiferromagnet are explicitly calculated to elucidate the cooling field dependence of loop bias, which is governed by distinct mechanisms at the flat and curved interfaces.

Spin glass properties mapped by coercivity in ferromagnet/spin glass bilayers.

We report on a study on the spin glass (SG) anisotropy (K ) and interfacial exchange coupling (J ) dependent coercivity (H ) at the ferromagnet/SG interface, based on a modified Monte Carlo Metropolis algorithm. It is shown that K and J are interdependent while taking effect on different magnetic degrees of freedom and different time scales, resulting in complicated H behaviors. By means of a micromagnetic approximation approach, we analytically explain the H behaviors with respect to K and J .

Creation and Annihilation of Skyrmions in the Frustrated Magnets with Competing Exchange Interactions.

In triangular-lattice magnets, the coexistence of third-neighbor antiferromagnetic and nearest-neighbor ferromagnetic exchange interactions can induce rich magnetic phases including noncoplanar skyrmion crystals. Based on Monte Carlo simulation, we studied the dependence of magnetic phase transition on exchange interaction strength. Under the consideration of uniaxial anisotropy and magnetic field both perpendicular to the film plane, a large antiferromagnetic exchange interaction induces a high frustration.