EVIDENCE FOR TWO-BAND MAGNETOTRANSPORT IN MnAs EPITAXIAL FILMS

LAURA B. STEREN, JULIAN MILANO, M. EDDRIEF, V.H. ETGENS, V. GARCIA, M. MARANGOLO

S.C. de Bariloche

Conferencia; 13th International Conference on Solid Films and Surfaces.; 2006

Centro Atomico Bariloche

Metallic MnAs is a promising material for uses in semiconductor-based spintronic devices. In fact, bulk MnAs is ferromagnetic at room temperature and has an hexagonal structure (alpha) whose lattice parameters match very well with those of GaAs. The MnAs undergoes a first order transition at T*=40 C between the low temperature hexagonal ferromagnetic phase and a paramagnetic orthorhombic one. The structural and magnetic properties of MnAs films are strongly affected by growth conditions and substrate. In this work we present a study of the transverse magnetoresistance and Hall effect of ferromagnetic MnAs thin films. The experimental results put in evidence the coexistence of both, hole and electron carriers. The temperature dependence of the ordinary Hall constant and the transverse magnetoresistance allow us to identify a transition between electron- and hole-dominated transport regimes. The effect of the substrate on the transport properties of the samples is noticeable and  will be discussed in the presentation.