Magneto-transport in MnAs/GaAs(100) nano-ribbons

FERNANDEZ BALDIS, F.,SIRENA, M., STEREN, L.,ETGENS, V. AND EDDRIEF, M.

Buenos Aires

Conferencia; X Latin-American Workshop on Magnetism, Magnetic Materials and their Applications; 2013

Hybrid metal/semiconductor systems are very interesting in spintronics. In particular, MnAs is a magnetic metal that grows epitaxially on the semiconductor GaAs. A lot of work has been made towards the understanding of charge transport and magnetism in these systems [1]. Bulk MnAs has a TC aprox 40 o C, where magnetic and structural rst-order phase transitions occur. At this temperature, the lowtemperature hexagonal ferromagnetic structure turns into an orthorhombic paramagnetic one. Films of MnAs grown in GaAs(100) present a coexistence of these two phases in a nite range of temperature, from 10 o C to 50 o C, due to strains induced by the substrate on the metallic lm. The integration of this material into spintronic devices requires a complete knowledge of its magneto-transport properties in micro and nano- sized structures. Previous work with nano-ribbons (NR) showed a dependence of the surface magnetic order and magnetic domains structure with the connement orientation and sample sizes [2,3]. In this work, we will present electronic-transport measurements carried out in NR with dierent sizes, ranging from 20x1x0:3m3 to 20x0:25x0:3m3, patterned by electron beam lithography on a 300nm-thick MnAs/GaA(001) lm grown by MBE. The electrical contacts are patterned by optical lithography onto the NR. The results of the Hall eect and magnetoresistance measurements performed at dierent temperatures allow us to investigate the charge carriers nature and the dominant transport mechanisms of the system. [1] J. J. Berry et al. Phys. Rev. B 64, 052408 (2001). [2] M. Tortarolo et al., Phys. Rev. B 81, 224406 (2010). [3] M. Tortarolo et al.,Journal of Applied Physics 112 (1), 013915 (2012).