Size effects on the alpha/beta phase coexistence in MnAs/GaAs (001) ribbons

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

Valparaiso

Conferencia; SOLIDOS 09; 2009

In this work we present  a systematic analysis of MnAs ribbons of different sizes and orientations fabricated by electron lithography from single-crystaline films of MnAs/GaAs(001).  We observed that the confinement effects not only depend on the size, but they also depend on the direction respect to the stripes in which the dimensions of the system are reduced. In the MnAs ribbons confined in the MnAs[0001] direction (c axis of the hexagonal lattice), the characteristic stripes pattern is not altered up to a confinement size of 100 nm . Nevertheless, for the ribbons confined inthe [11-20] direction, the topographic and magnetic properties are substantially altered below a lateral confinement size of of 2 mm. Although the phase coexistence occurs for every studied size, the stripe pattern due to the phase coexistence is modified by a redistribution of the phases owed to the relaxation of the epitaxial strains.