Study of the influence of surface anisotropy and lattice structure on the behaviour of a small magnetic cluster

TL;DR

This study uses Monte Carlo simulations to explore how surface anisotropy and lattice structure influence the thermal and magnetic behavior of small clusters, revealing structure-dependent effects on hysteresis and thermal properties.

Contribution

It introduces a detailed analysis of small magnetic clusters considering different lattice structures and surface anisotropy effects, highlighting their impact on magnetic behavior.

Findings

Thermal behavior varies with lattice structure and anisotropy constant.

Hysteresis cycles exhibit step-like features depending on field orientation.

Surface anisotropy and lattice structure significantly influence magnetic responses.

Abstract

We have studied by Monte Carlo simulations the thermal behaviour of a small (N=13 particles) cluster described by a Heisenberg model, including nearest-neighbour ferromagnetic interactions and radial surface anisotropy, in an applied magnetic field. We have studied three different lattice structures: hexagonal close packed, face centered cubic and icosahedral. We show that the zero-field thermal behaviour depends not only on the value of the anisotropy constant but also on the lattice structure. The behaviour in an applied field, additionally depends, on the different orientations of the field with respect to the crystal axes. According to these relative orientations, hysteresis cycles show different step-like characteristics.