Spin- and orbital-moment compensation in the zero-moment ferromagnet Sm0.974Gd0.026Al2.

4 pagesInternational audienceThe balance between the orbital and spin magnetic moments of Sm3+ in the zero-moment ferromagnet Sm0.974Gd0.026Al2 has been studied using x-ray magnetic circular dichroism (XMCD) at the Sm M4,5 edges. The difference in the XMCD multiplet structure below and above the compensation point, Tcomp, demonstrates that the exchange and crystal-field interactions mix the low-lying 7=7/2 excited state into the Sm f5 6H5/2 ground state. Sum-rule analysis of the temperature-dependent XMCD reveals an anomalous change in the Sm3+ orbital to spin magnetic-moment ratio as the net magnetization vanishes at Tcomp. This behavior is ascribed to the role of the conduction electron-spin moment which couples parallel to the Sm spin moment