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

¹ IPCMS-GEMM, ULP-CNRS, UMR 046, 23 rue du Loess 67037 Strasbourg, France
² SIEMENS AG, D-91052 Erlangen, Germany

Received: 25 August 1997
Accepted: 16 March 1998

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 at 4.2 K. This interlayer coupling is strong and is supported by ab initio calculations of the magnetization. Very strong variation of the exchange coupling has been observed between room temperature and 4.2 K and is attributed to the strong intermixing at the Co/Ir interfaces.