Nature of the Perpendicular-to-Parallel Spin Reorientation in a Mn-doped GaAs Quantum Well: Canting or Phase Separation?

Abstract

It is well known that the magnetic anisotropy in a compressively-strained Mn-doped GaAs film changes from perpendicular to parallel with increasing hole concentration $p$. We study this reorientation transition at T=0 in a quantum well with Mn impurities confined to a single plane. With increasing $p$, the angle $\theta$ that minimizes the energy $E$ increases continuously from 0 (perpendicular anisotropy) to $\pi /2$ (parallel anisotropy) within some range of $p$. The shape of $\Emin (p)$ suggests that the quantum well becomes phase separated with regions containing low hole concentrations and perpendicular moments interspersed with other regions containing high hole concentrations and parallel moments. However, due to the Coulomb energy cost associated with phase separation, the true magnetic state in the transition region is canted with $0<\theta <\pi /2$.

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Cited by in corpus (2)

• Phase diagram for Coulomb-frustrated phase separation in systems with negative short-range compressibility
• Coarse grained models in Coulomb-frustrated phase separation