Magnetism and effect of anisotropy with one dimensional monatomic chain of cobalt by a Monte Carlo simulation

TL;DR

This study uses Monte Carlo simulations to explore the magnetic behavior of a one-dimensional cobalt monatomic chain, reproducing experimental features and analyzing the effects of anisotropy, exchange interactions, and dynamics on coercivity and hysteresis.

Contribution

It introduces a detailed Monte Carlo simulation model that captures the temperature-dependent magnetic properties and hysteresis behavior of 1D Co chains, including the effects of anisotropy and dynamical processes.

Findings

Normalized coercivity follows a universal temperature dependence.

Simulation reproduces experimental temperature-dependent coercivity.

Open hysteresis loops result from slow dynamical processes.

Abstract

The magnetic properties of the one dimensional (1D) monatomic chain of Co reported in a previous experimental work are investigated by a classical Monte Carlo simulation based on the anisotropic Heisenberg model. In our simulation, the effect of the on-site uniaxial anisotropy, Ku, on each individual Co atom and the nearest neighbour exchange interaction, J, are accounted for. The normalized coercivity HC(T)/HC(TCL) is found to show a universal behaviour, HC(T)/HC(TCL) = h0(e^{TB/T}-e) in the temperature interval, TCL < T < TBCal, arising from the thermal activation effect. In the above expression, h0 is a constant, TBCal is the blocking temperature determined by the calculation, and TCL is the temperature above which the classical Monte Carlo simulation gives a good description on the investigated system. The present simulation has reproduced the experimental features, including the temperature dependent coercivity, HC(T), and the angular dependence of the remanent magnetization, MR(phi,theta), upon the relative orientation (phi,theta) of the applied field H. In addition, the calculation reveals that the ferromagnetic-like open hysteresis loop is a result of a slow dynamical process at T < TBCal. The dependence of the dynamical TBCal on the field sweeping rate R, the on-site anisotropy constant Ku, and the number of atoms in the atomic chain, N, has been investigated in detail.