Eur. Phys. J. B 81, 49-62 (2011)
https://doi.org/10.1140/epjb/e2011-11004-8

Crystal field effect on X-ray magnetic circular dichroism spectra at the L_2,3 absorption edges of mixed-valence Ce and Yb compounds in high magnetic fields

¹ Photon Factory, Institute of Materials Structure Science, 1-1 Oho, Tsukuba, 305-0801, Ibaraki, Japan
² RIKEN SPring-8 Center, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun 679-5148, Hyogo, Japan

Corresponding author: ^a kotani@spring8.or.jp

Received: 22 December 2010
Revised: 25 February 2011
Published online: 13 April 2011

Abstract

A theoretical study is presented, with an extended single impurity Anderson model, for the crystal field effect on the X-ray magnetic circular dichroism (XMCD) spectra at L_2,3 edges of mixed-valence Ce and Yb compounds in high magnetic fields. The crystal field acting on the 4f electrons is assumed to have cubic symmetry. Due to the competition among the effects of crystal field, mixed valency, and external magnetic field, the magnetic-field-dependence of XMCD spectra exhibits a variety of features; for instance, the branching ratio, R(L₂/L₃), of L₂ and L₃ XMCD intensities of Ce compounds can take R(L₂/L₃) > 1.0 and <1.0, and that of Yb compounds can take R(L₂/L₃) > 0 and <0. It is shown that the magnetic-field-dependence of the total XMCD intensity I(L₂ + L₃) is proportional to the magnetization curve, but that of R(L₂/L₃) gives more precise information on the ground state wavefunction in magnetic fields. A new and useful method to correlate the XMCD spectra, the 4f magnetization and the ground state wavefunction is proposed and used to discuss the relation between I(L₂ + L₃) and the magnetization curve and that between R(L₂/L₃) and the ground state wavefunction.