A 90 degrees ferromagnetic layer coupling in FM/AFM/FM structures

The magnetic anisotropy in the samples of Ta (5nm)/NiFe (8nm)/FeMn (t(AF))/ NiFe (8nm)/Ta (5nm) with t(AF) = 0-30 nm were studied by using a vibrating sample magnetometer (VSM) and ferromagnetic resonance (FMR). Unidirectional anisotropy field (H-B) and uniaxial anisotropy field (H-A) having strength comparable with literatures and easy axes in the direction of the field du ring deposition were observed in the bottom Py layers, a smaller H-B with e asy axis parallel to the deposition field in the top Py layer was also obse rved. An interesting finding was that an additional uniaxial anisotropy in the top Py layer appeared with the easy axis perpendicular to the direction of field during deposition. A possible explanation for the 90 degrees coup ling between the bottom and top Py layers through the intervening antiferro magnetic FeMn film is considered to be interface roughness. (C) 2001 Elsevi er Science B.V. All rights reserved.