XAFS studies of the behaviour of Bi in Co/Cu multilayers

Abstract

The atomic environment of Bi atoms in the Co/Cu multilayered system was studied with X-ray absorption fine structure spectroscopy. Experiments were carried out on a Co(1 nm)/Cu(2 nm) system with 5 and 10 repetitions of Co/Cu evaporated with very low deposition rate in ultrahigh vacuum. A very small amount of Bi (0.06 nm) was deposited on each Cu film in the system. The X-ray absorption fine structure spectra were measured at the BiL3 edge in the X-ray absorption near-edge structure and extended X-ray absorption fine structure ranges at the Beamline X1 of HASYLAB/DESY synchrotron laboratory in Hamburg. The experimental data showed different local neighbourhood of Bi, depending on the number of Co/Cu bilayer repetitions. The results are discussed in terms of the location and segregation of the Bi atoms as well as its possible oxidation ways.