Spin relaxation of Mn + h complexes in III-V semiconductors

Splitting between heavy and light hole levels is known to results in long spin relaxation times of holes confined in compressively strained InAs quantum dots [1]. We show theoretically that $T_{1}$ can be elongated by orders of magnitudes if the hole resides on a Mn acceptor, as the $p-d$ exchange interaction introduces a magnetic anisotropy barrier for spin relaxation. In order to compare the magnitudes of thermally activated over-barrier spin relaxation with a competing non-stationary quantum tunnelling at level anticrossings we evaluate also the expected magnitude of the ground state splitting by various intrinsic and extrinsic effects, including random in-plane strains. The relevance of our results for optical [2] and transport studies [3] of Mn-containing InAs quantum dots and quantum wells, respectively is examined and shown to elucidate the origin of the observed anisotropies and hystereses. \\[4pt] [1] D. Heiss et al., \textit{Phys. Rev. B} 76, 241306(R) (2007). \\[0pt] [2] O Krebs et al., \textit{Phys. Rev. B} 80, 165315 (2009).\\[0pt] [3] U. Wurstbauer et al., \textit{J. Crystal Growth} 311, 2160 (2009); \textit{Phys. Rev. B }79, 155444 (2009); \textit{Phys. E} [doi:10.1016/j.physe.2009.11.012].