We present magnetic and tunnel transport properties of (Ga,Mn)As/(In,Ga)As/(Ga,Mn)As structure before and after adequate annealing procedure. The conjugate increase of magnetization and tunnel magnetoresistance obtained after annealing is shown to be associated to the increase of both exchange energy Δexch and hole concentration by reduction of the Mn interstitial atom in the top magnetic electrode. Through a 6x6 band k.p model, we established general phase diagrams of tunneling magnetoresistance (TMR) and tunneling anisotropic magnetoresistance (TAMR) \textit{vs.} (Ga,Mn)As Fermi energy (EF) and spin-splitting parameter (BG). This allows to give a rough estimation of the exchange energy Δexch=6BG≃120 meV and hole concentration p≃1.1020cm−3 of (Ga,Mn)As and beyond gives the general trend of TMR and TAMR \textit{vs.} the selected hole band involved in the tunneling transport.
@article{arxiv.0706.0109,
title = {Spin-Polarized Tunneling as a probe of (Ga,Mn)As electronic properties},
author = {M. Elsen and H. Jaffres and R. Mattana and L. Thevenard and A. Lemaitre and J. -M. George},
journal= {arXiv preprint arXiv:0706.0109},
year = {2007}
}