Experimental observation of temperature and magnetic-field evolution of the 4f states in CeFe2 revealed by soft x-ray magnetic circular dichroism
AbstractWe revisit the delocalized character of the 4f states of CeFe2 in the ferromagnetically ordered phase by x-ray magnetic circular dichroism (XMCD) in x-ray absorption spectroscopy (XAS) with improved data quality using single crystals. Surprisingly, the Ce M4,5 XMCD spectral shape changes significantly as a function of temperature and applied magnetic field, with no concomitant changes in the spectral shape of the Ce M4,5 XAS as well as the Fe L2,3 XAS and XMCD. This unusual behavior is characterized by the J=7/2 states in a 4f1 configuration mixed into the J=5/2 ground state. Such extreme sensitivity of the Ce 4f states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe2. Our experimental data presented here provide valuable insights into the underlying physics in strongly hybridized ferromagnetic Ce compounds.