相关论文: Effect of anisotropy on small magnetic clusters
The influence of surface anisotropy on the magnetization processes of maghemite nanoparticles with ellipsoidal shape is studied by means of Monte Carlo simulations. Radial surface anisotropy is found to favor the formation of hedgehog-like…
A recent theory of magnetoresistance in positionally disordered organic semiconductors is extended to include exchange and dipolar couplings between polarons. Analytic results are discovered when the hyperfine, exchange, and dipolar…
The relaxation rate and temperature-dependent switching field curve of a spherical magnetic nanocluster are calculated by taking into account the effect of surface anisotropy via an effective anisotropy model. In particular, it is shown…
Entanglement, magnetization and magnetic susceptibility for 1D antiferromagnetic spin 1 and spin 3/2 Heisenberg XXX model with Dzyaloshinskii-Moriya interaction, single-ion anisotropy and external magnetic field on the finite chain are…
We present a review of recent advances in the study of many-body effects in magnetic nanoparticles. Considering classical spins on a lattice coupled by the exchange interaction in the presence of the bulk and surface anisotropy, we…
We theoretically investigate the effect of an anisotropic trap on the instability of the polar $(m_F=0)$ phase of a spin-1 Bose-Einstein condensate. By considering rigorously the spatial quantization, we show that the growth of the nascent…
The magnetic phase diagram and low-energy magnon excitations of structurally and magnetically chiral MnSb2O6 are reported. The specific heat and the static magnetization are investigated in magnetic fields up to 9 and 30 T, respectively,…
We investigate analytically and numerically the ground and metastable states for easy-plane Heisenberg magnets with single-ion surface anisotropy and disk geometry. The configurations with two half-vortices at the opposite points of the…
We investigate the thermally activated magnetization switching of small ferromagnetic particles driven by an external magnetic field. For low uniaxial anisotropy the spins can be expected to rotate coherently, while for sufficient large…
We analyze the impact of the magnetic anisotropy on the geometric structure and magnetic ordering of small atomic clusters of palladium, iridium, platinum and gold, using Density Functional Theory. Our results highlight the absolute need to…
The antiferromagnetic Heisenberg model on icosahedral symmetry $I_{h}$ fullerene clusters exhibits unconventional magnetic properties, despite the lack of anisotropic interactions. At the classical level, and for number of sites $n \leq…
The effect of the anisotropy in the exchange interaction on the phase diagrams and magnetization behavior of the Heisenberg thin film has been investigated with effective field formulation in a two spin cluster using the decoupling…
The generalized Fisher super-exchange antiferromagnetic model with uniaxial crystal-field anisotropy is exactly investigated using an extended mapping technique. An exact relation between partition function of the studied system and that…
The ground-state properties of the square-lattice spin-1/2 Heisenberg antiferromagnet with spatially anisotropic couplings are investigated by Green's-function projection approaches. The staggered magnetization and the two-spin correlators…
We study the finite-size and surface effects on the thermal and spatial behaviors of the magnetisation of a small magnetic particle. We consider two systems: 1) A box-shaped isotropic particle of simple cubic structure with either periodic…
The thermally activated magnetic relaxation in two-dimensional ensembles of dipolar interacting nanoparticles with large uniaxial perpendicular anisotropy is studied by a numerical method and within the mean-field approximation. The role…
Magnetic properties of the spin-1/2 XXZ Heisenberg cuboctahedron are examined using exact numerical diagonalization depending on a relative strength of the exchange anisotropy. While the Ising cuboctahedron exhibits in a low-temperature…
We study the magnetic structure of the ground state of an itinerant Fermi system of spin-\nicefrac{1}{2} particles with magnetic dipole-dipole interactions. We show that, quite generally, the spin state of particles depend on its momentum,…
Using exact diagonalization, Monte-Carlo, and mean-field techniques, characteristic temperature scales for ferromagnetic order are discussed for the Ising and the classical anisotropic Heisenberg model on finite lattices in one and two…
Assemblies of magnetic nanoparticles exhibit interesting physical properties arising from the competition of intraparticle dynamics and interparticle interactions. In ordered arrays of magnetic nanoparticles magnetostatic interparticle…