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

Abstract

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 °C and is accompanied by a change in the crystallographic orientation from 〈1 1 1〉 to 〈1 0 0〉 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 Ni x Fe (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 Ni x Fe (1− x) layer. Moreover, the degree of lattice mismatch exerts a critical influence on the recrystallization probability.