Mismatch-induced recrystallization of giant magneto-resistance (GMR) multilayer systems

The giant magneto-resistance (GMR) multilayer systems NiFe/Cu and Co/Cu have been studied regarding thermally induced recrystallization. The microstructural reaction takes place during brief annealing at 350-450 degrees C and is accompanied by a change ill the crystallographic orientation from < 1 1 1 > to < 100 > wire texture. The reaction may be utilized to produce GMR sensor layers of remarkable thermal stability. It is shown that the crystallographic reorientation is triggered by the minimization of lattice mismatch elastic energy. Although the systems of interest are equivalent in respect of the observed phenomenon, the NixFe(1-x)/Cu system is chosen for a detailed analysis because it allows for precise control of the lattice constant by varying the Fe content in the NixFe(1-x) layer. Moreover, the degree of lattice mismatch exerts a critical influence on the recrystallization probability. (c) 2007 Acta Materialia Inc. Published by Flsevier Ltd. All rights reserved.