Anisotropic magnetic-field-induced phase transition in MnAs nanoribbons

F. Fernandez Baldis (1, 2) , Martín Sirena (1, 2) , Laura B. Steren (3, 1) , Victor H. Etgens (4) , M. Eddrief (4) , C. Ulysse (5) , G. Faini (5)

1 CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas [Buenos Aires]
2 Instituto Balseiro [Bariloche]
3 CAC - Centro Atómico Constituyentes
4 INSP-E8 - Croissance et propriétés de systèmes hybrides en couches minces
5 LPN - Laboratoire de photonique et de nanostructures

MnAs thin films present a phase coexistence of regularly arranged ferromagnetic (α) and paramagnetic (β) stripes below the Curie temperature when grown onto GaAs(100) substrates. In this letter, we report the observation of a magneto-structural phase transition induced by magnetic field on MnAs nanoribbons below the Curie temperature. A transformation of high-resistance paramagnetic regions into low-resistance ferromagnetic ones is observed above temperature-dependent critical magnetic fields. The phenomenon is hysteretic, highly anisotropic, and size dependent and could be the origin of the high magneto-resistance effect observed at temperatures close to room temperature in these systems.

Domaines: Physique [physics]

F. Fernandez Baldis, Martín Sirena, Laura B. Steren, Victor H. Etgens, M. Eddrief, et al.. Anisotropic magnetic-field-induced phase transition in MnAs nanoribbons. Applied Physics Letters, 2015, 107 (1), pp.012407. ⟨10.1063/1.4926567⟩. ⟨hal-01442941⟩