Confinement effects in magnetism of thin MnAs ribbons

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

Buenos Aires

Congreso; At the frontiers of Condensed Matter IV; 2008

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Thin films of MnAs grown on GaAs substrates have been intensively studied during the last ten years. The coexistence of two different phases, hexagonal-ferromagnetic and orthorhombic-paramagnetic, was reported for these films at room temperature, despite not being observed 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 systematic analysis of MnAs ribbons of different sizes and orientations fabricated by electron lithography from epitaxial films of MnAs/GaAs(100). The topography and the magnetic domain behaviour of the ribbons were characterized by atomic and magnetic force microscopy. This characterization was focused  on the reversal mechanisms of the stripes magnetization and on the effects of lateral confinement on the phase coexistence  of  MnAs films.