Pseudo spin‐valve structures with NiO/Co as a hard magnetic layer

Abstract

AbstractA key problem in some applications of pseudo spin‐valve structures (PSV) is the choice of appropriate materials for soft and hard ferromagnetic layers and their thickness to ensure a high difference in the switching fields. We show that this can be achieved using a NiO/Co structure as a hard magnetic layer. By varying the thickness of the constituent layers, good symmetrical switching characteristics have been shown in PSV structures with NiO/Co as a hard magnetic layer. The most important features of our PSV structures with suitable selected thickness of particular layers are: a relatively high value of GMR amplitude (up to 9% at RT) due to a possible electron specular reflection at the NiO/Co interfaces, a high coercivity (∼500 Oe) of hard magnetic layer resulted from a specific interaction of a 15 nm thick antiferromagnetic NiO with a 2 nm thick Co layer, nearly symmetrical magnetoresistance transfer curves MR(H) due to negligible unidirectional anisotropy field of NiO/Co bilayer with NiO thickness <15 nm. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)