CONTRIBUTION OF CURRENT PERPENDICULAR TO THE PLANE TO THE GIANT MAGNETORESISTANCE OF LATERALLY MODULATED SPIN VALUES

Giant magnetoresistance (GMR) effects up to 10% have been observed in Co/Cu/FeNi spin valve structures grown onto step bunched vicinal Si(ll l)substrates misoriented towards [11-2]. The step bunching is activate d using a simple thermal treatment which Il-ads to surfaces where terr aces alternate with facets at the nanometer scale. GMR of the spin val ve structures is investigated with the current applied parallel or per pendicular to the steps. An in-plane uniaxial magnetic anisotropy is i nduced in each magnetic layer with the easy axis parallel to the steps . This results in square GMR behavior when the field is applied along the easy axis. Specific features observed when the field is applied al ong the hard axis are also shown to be the consequence of this anisotr opy. When the initial misorientation angle of the substrate becomes hi gher than 4 degrees, we observe an enhancement of the room-temperature GMR when the current is applied perpendicular to the steps. The origi n of this enhancement is discussed based on the temperature dependence of this effect. (C) 1997 American Institute of Physics.