Magnetoresistive tunnel junctions deposited on laterally modulated substrates

Co/Al2O3/NiFe tunnel junctions were deposited on misoriented silicon substr ates. A thermal treatment activates a step bunching mechanism on the silico n surface leading to a modulated topology with a nanometric lateral period. The bottom magnetic electrode and the barrier follow this topology. Such j unctions present good magnetotransport characteristics with a magnetoresist ance about 14% at room temperature. Due to the uniaxial anisotropy induced by the topological modulation, the antiparallel configuration of the magnet ization is well defined leading to perfect square magnetoresistance cycles at all temperatures. The magnetic behavior of patterned junctions has been investigated by transport measurements and Kerr microscopy. More than induc ing a strong uniaxial anisotropy, the modulated topology is shown to strong ly influence the switching mechanism of the magnetization. (C) 2000 America n Institute of Physics. [S0003-6951(00)04522-8].