X-ray magnetic circular dichroism temperature dependent study of RCo2 compounds

We have performed a temperature-dependent study of the rare earth L-2,L-3 a nd Co K edges x-ray magnetic circular dichroism (XMCD) in HoCo2 and PrCo2. We have found in both samples that the L-2/L-3 ratio is temperature indepen dent. This result contradicts previous findings that indicated a possible d ifferent behavior for L-2 and L-3 edges owing to modifications in the degre e of 3d-5d hybridization. A further interesting result is that the temperat ure dependence of ratio E-1/E-2 for the L-3 edge - where E-1 and E-2 corres pond to the two area under the dichroic signal separated in two peaks, posi tive dipolar dominant, negative with significant contributions of both dipo lar and quadrupolar channels - is also constant, suggesting that the dipola r and quadrupolar channels follow the same temperature dependence. This eff ect might be interpreted as the dominant 4f contribution to the 5d polariza tion (much larger than the 3d-induced contribution) to create the L-edge XM CD signal. The microscopic origin of the metamagnetic Co subsystem is also addressed. (C) 2000 American Institute of Physics. [S0021-8979(00)50308-9].