Dynamics of diluted magnetic semiconductors from atomistic spin dynamics simulations: Mn doped GaAs as a case study

Abstract

The dynamical behavior of the magnetism of diluted magnetic semiconductors (DMS) has been investigated by means of atomistic spin dynamics simulations. The conclusions drawn from the study are argued to be general for DMS systems in the low concentration limit, although all simulations are done for 5% Mn-doped GaAs with various concentrations of As antisite defects. The magnetization curve, $M(T)$, and the Curie temperature $T_C$ have been calculated, and are found to be in good correspondence to results from Monte Carlo simulations and experiments. Furthermore, equilibrium and non-equilibrium behavior of the magnetic pair correlation function have been extracted. The dynamics of DMS systems reveals a substantial short ranged magnetic order even at temperatures at or above the ordering temperature, with a non-vanishing pair correlation function extending up to several atomic shells. For the high As antisite concentrations the simulations show a short ranged anti-ferromagnetic coupling, and a weakened long ranged ferromagnetic coupling. For sufficiently large concentrations we do not observe any long ranged ferromagnetic correlation. A typical dynamical response shows that starting from a random orientation of moments, the spin-correlation develops very fast ($\sim$ 1ps) extending up to 15 atomic shells. Above $\sim$ 10 ps in the simulations, the pair correlation is observed to extend over some 40 atomic shells. The autocorrelation function has been calculated and compared with ferromagnets like bcc Fe and spin-glass materials. We find no evidence in our simulations for a spin-glass behaviour, for any concentration of As antisites. Instead the magnetic response is better described as slow dynamics, at least when compared to that of a regular ferromagnet like bcc Fe.

24 pages, 15 figures

References in corpus (5)

• A method for atomistic spin dynamics simulations: implementation and examples
• Origin and control of high-temperature ferromagnetism in semiconductors
• Enhanced annealing, high Curie temperature and low-voltage gating in (Ga,Mn)As: A surface oxide control study
• Magnetic spin excitations in diluted ferromagnetic systems: the case of $G{a}_{1-x}M{n}_{x}As$
• Superexchange induced canted ferromagnetism in dilute magnets

Cited by in corpus (9)

• Stable and fast semi-implicit integration of the stochastic Landau-Lifshitz equation
• Equation of state of paramagnetic CrN from ab initio molecular dynamics
• Anomalous phonon lifetime shortening in paramagnetic CrN caused by magneto-lattice coupling: A combined spin and ab initio molecular dynamics study
• Realization of the thermal equilibrium in inhomogeneous magnetic systems by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its dynamical aspects
• Exchange Interactions in Paramagnetic Amorphous and Disordered Crystalline CrN-based Systems
• Atomistic spin dynamics of the CuMn spin glass alloy
• Ultrafast cooling and heating scenarios for the laser induced phase transition in CuO
• Magnetic properties of Mn-doped Bi${}_2$Se${}_3$ topological insulators: ab initio calculations
• Spin dynamics of Mn impurities and their bound acceptors in GaAs