Exchange coupling and magnetoresistance in Co/Ir multilayersprepared by ion beam sputtering

Abstract

A series of Co/Ir multilayers has been prepared by Ion Beam Sputtering on a glass substrate covered by a Fe(10 nm)/Ir(10 nm) buffer layer. The Co thickness has been fixed at 3 nm and the Ir thickness varied between 0.1 and 2.4 nm. X-ray diffraction patterns performed on these multilayers show an fcc structure with a (111) preferential texture. The antiferromagnetic (AFM) exchange coupling and magnetoresistance show an oscillating behavior as a function of the Ir thickness with a period of about 1 nm. The first AFM peak has been observed at the 0.6 nm thick Ir spacer layer and its strength corresponds to JAF = − 6 erg/cm2 at 4.2 K. This interlayer coupling is strong and issupported by ab initio calculations of the magnetization. Very strongvariation of the exchange coupling has been observed between room temperatureand 4.2 K and is attributed to the strong intermixing at the Co/Ir interfaces.