Confinement effects in magnetism of thin MnAs ribbon

M. TORTAROLO; M. SIRENA; J. MILANO; L. B. STEREN; V. H. ETGENS; M. EDDRIEF

Buenos Aires, Argentina

Conferencia; At the frontiers of Condensed Matter 2008; 2008

Thin films of MnAs grown on GaAs substrates have been intensively studied during the last ten years. The coexistence of two different phases, hexagonal (alpha- MnAs) and orthorhombic (beta-MnAs) was reported for these films at room temperature, despite not beingobserved in bulk material. A periodic arrangement of these two phases in microscopic stripes is observed when the MnAs films are grown on GaAs (100) substrates. Many recent works show the effects of the lateral nanostructuration of the films, particularly, on the magnetic domain arrangement in MnAs dots of different sizes. In this work we present a systematicanalysis of MnAs ribbons of different sizes and orientations fabricated by electron lithography from monocrystaline films of MnAs grown on GaAs. The topography and the magnetic domain behaviour of the ribbons were characterised by atomic and magnetic force microscopy. This characterisation is focused in the reversal mechanisms of the stripes magnetisationand the effects of lateral confinement on the coexistence of both phases (magnetic alpha and non-magnetic beta) present in MnAs films.