Positional Disorder, Spin-Orbit Coupling and Frustration in GaMnAs

Abstract

We study the magnetic properties of metallic GaMnAs. We calculate the effective RKKY interaction between Mn spins using several realistic models for the valence band structure of GaAs. We also study the effect of positional disorder of the Mn on the magnetic properties. We find that the interaction between two Mn spins is anisotropic due to spin-orbit coupling within both the so-called spherical approximation and in the more realistic six band model. The spherical approximation strongly overestimates this anistropy, especially for short distances between Mn ions. Using the obtained effective Hamiltonian we carry out Monte Carlo simulations of finite and zero temperature magnetization and find that, due to orientational frustration of the spins, non-collinear states appear in both valence band approximations for disordered, uncorrelated Mn impurities in the small concentration regime. Introducing correlations among the substitutional Mn positions or increasing the Mn concentration leads to an increase in the remnant magnetization at zero temperature and an almost fully polarized ferromagnetic state.

17 Pages, 13 Figures

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Cited by in corpus (20)

• Theory of ferromagnetic (III,Mn)V semiconductors
• Prospects of high temperature ferromagnetism in (Ga,Mn)As semiconductors
• Why RKKY exchange integrals are inappropriate to describe ferromagnetism in diluted magnetic semiconductors
• Low-temperature magnetization of (Ga,Mn)As semiconductors
• Influence of non-local exchange on RKKY interactions in III-V diluted magnetic semiconductors
• Emergence of noncollinear magnetic ordering in small magnetic clusters: Mn${}_n$ and As@Mn${}_n$
• Spin-orientation-dependent spatial structure of a magnetic acceptor state in a zincblende semiconductor
• Carrier induced ferromagnetism in diluted local-moment systems
• Scaling analysis of the magnetoresistance in Ga_{1-x}Mn_xAs
• Dielectric function of the semiconductor hole gas
• Dielectric function of the semiconductor hole liquid: Full frequency and wave vector dependence
• Disorder, spin-orbit, and interaction effects in dilute ${\mathrm{Ga}}_{1-x}{\mathrm{Mn}}_x\mathrm{As}$
• The influence of structural short-range order on the phase diagrams of diluted FCC magnet with arbitrary spin and modified RKKY interaction
• Carrier-density-controlled anisotropic spin susceptibility of two-dimensional hole systems
• A single layer of Mn in a GaAs quantum well: a ferromagnet with quantum fluctuations
• Effects of dilution and disorder on magnetism in diluted spin systems
• Heitler-London model for acceptor-acceptor interactions in doped semiconductors
• RKKY interaction induced by two-dimensional hole gases
• Possible magnetic-field-induced voltage and thermopower in diluted magnetic semiconductors
• Enhanced ferromagnetism from electron-electron interactions in double exchange type models