Magnetic and electronic properties of Ce(111) thin films

Epitaxial gamma-Ce thin films, stabilised at low temperatures when sandwich ed by W(110) buffer and capping layers, have been studied by X-ray absorpti on spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) in a tem perature range of 5-300 K and with an applied magnetic field mu(0)H = 0-7 T , at the M-4,M-5 edges on the beamline ID12B at ESRF. The mean 4f occupancy , nf, was found to be intermediate to that of alpha and gamma-phases, which is proposed to arise from an increase of the valence at the W/Ce interface . In addition, a reversible decrease of n(f) is observed when the temperatu re is decreased from which we estimate a bulk Ce Kondo temperature T-K = 15 0 K. The XMCD shows that Ce is Curie-Weiss paramagnetic down to the lowest examined temperature with small \theta(p)\ < 10 K in contrast to the high T -K Obtained from the XAS. (C) 1999 Elsevier Science B.V. All rights reserve d.