Magnetic spin excitations in diluted ferromagnetic systems: the case of $G{a}_{1-x}M{n}_{x}As$

Abstract

We propose a theory which allow to calculate the magnetic excitation spectrum in diluted ferromagnetic systems. The approach is rather general and based on the Self-Consistent local Random Phase Approximation in which disorder (dilution) and thermal fluctuations are properly treated. To illustrate its reliability and accuracy we calculate the magnetic excitation in the diluted III-V magnetic semiconductor $G{a}_{1-x}M{n}_{x}As$. It is shown that dilution has a drastic effect on the excitation spectrum, indeed well defined magnon excitations exist only in a small region of the Brillouin zone centered around the $\Gamma$ point. We also calculate the spin stiffness in optimally annealed sample as a function of $M{n}^{2+}$ concentration. A comparison to available measurements is done. We find a very good agreement for both the Curie temperature and the spin stiffness measured in well annealed samples and provide a plausible explanation for the very small values measured in as grown samples.

arXiv commentThe manuscript has been modified, 4 figures are included. Accepted for publication in Eur. Phys. Lett

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Cited by in corpus (11)

• Dilute ferromagnetic semiconductors: Physics and spintronic structures
• Spin-dependent phenomena and device concepts explored in (Ga,Mn)As
• Theory of spin waves in ferromagnetic (Ga,Mn)As
• Dynamics of diluted magnetic semiconductors from atomistic spin dynamics simulations: Mn doped GaAs as a case study
• Dynamical properties of a three-dimensional diluted Heisenberg model
• Magnetic spin excitations in Mn doped GaAs : A model study
• Methods of electron transport in ab initio theory of spin stiffness
• Effective Heisenberg exchange integrals of diluted magnetic semiconductors determined within realistic multi-band tight-binding models
• Spin-wave excitations in presence of nanoclusters of magnetic impurities
• Lifetimes of Magnons in Two-Dimensional Diluted Ferromagnetic Systems
• Coherence and stiffness of spin waves in diluted ferromagnets