Quantitative simulation of temperature-dependent magnetization dynamics and equilibrium properties of elemental ferromagnets

Abstract

Atomistic spin model simulations are immensely useful in determining temperature dependent magnetic properties, but are known to give the incorrect dependence of the magnetization on temperature compared to experiment owing to their classical origin. We find a single parameter rescaling of thermal fluctuations which gives quantitative agreement of the temperature dependent magnetization between atomistic simulations and experiment for the elemental ferromagnets Ni, Fe , Co and Gd. Simulating the sub-picosecond magnetization dynamics of Ni under the action of a laser pulse we also find quantitative agreement with experiment in the ultrafast regime. This enables the quantitative determination of temperature dependent magnetic properties allowing for accurate simulations of magnetic materials at all temperatures.

Calculating temperature-dependent properties of Nd2Fe14B permanent magnets by atomistic spin model simulations

“…Apart from the possible reason related to temperature or DLM-state dependent exchange parameters, we think the distinction between the quantum model and the classical model should also contribute to the deviation in Fig. 2(a), as thoroughly discussed in [48]. Atomistic spin model is a classical model which considers localized classical atomistic spins with unrestricted and continuous values.…”

Temperature-dependent exchange stiffness and domain wall width in Co

“…Note that in terms of the magnetization (and not temperature) the classical and quantum cases give similar behavior [45]. To overcome the problem of the incorrect temperature dependence of the magnetization in the simulation and to make our results more useful for comparison with experiments, we assume that the experimentally measured magnetization obeys the Curie-Bloch relation m(T ) = (1 − (T /T C ) α ) β with β = 0.34 and α = 2.369 for Co [46]. We then apply temperature rescaling as suggested in Ref.…”

Dynamic response in a finite size composite multiferroic thin film

“…Generally, the technique of the spin dynamics is used to solve the behavior of the magnetic moment due to an effective field in the micromagnetic model [18]. In this model, the magnetic moment is replaced by the spin moment in each individual magnetic spin.…”

“…To describe the time evolution of the spins' response, an differential equation named Landau-Lifshitz-Gilbert equation has been used at atomic level [1,18,27]. In Eq.…”