Experimental observation of temperature and magnetic-field evolution of the 4 states in CeFe revealed by soft X-ray magnetic circular dichroism

Saito, Yuji; Yasui, Akira*; Fuchimoto, Hiroto*; Nakatani, Yasuhiro*; Fujiwara, Hidenori*; Imada, Shin*; Narumi, Yasuo*; Kindo, Koichi*; Takahashi, Minoru*; Ebihara, Takao*; et al.

Physical Review B, 96(3), p.035151_1 - 035151_5, 2017/07

AA2017-0611.pdf:0.36MB

https://doi.org/10.1103/PhysRevB.96.035151

We revisit the delocalized character of the 4 states of CeFe 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 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 XAS as well as the Fe XAS and XMCD. This unusual behavior is characterized by the states in a 4 configuration mixed into the ground state. Such extreme sensitivity of the Ce 4 states to the external perturbations can be related to the magnetic instability toward an antiferromagnetic phase in CeFe. Our experimental data presented here provide valuable insights into the underlying physics in strongly-hybridized ferromagnetic Ce compounds.

X-ray magnetic circular dichroism at the edge of MnGaC

Takahashi, Manabu*; Igarashi, Junichi

Physical Review B, 67(24), p.245104_1 - 245104_5, 2003/06

https://doi.org/10.1103/PhysRevB.67.245104

We theoretically investigate the origin of the X-ray magnetic circular dichroism (XMCD) spectra at the K edge of Mn and Ga in the ferromagnetic phase of MnGaC on the basis of an ab initio calculation. Taking account of the spin-orbit interaction in the LDA scheme, we obtain the XMCD spectra in excellent agreement with the recent experiment. We have analyzed the origin of each structure, and thus elucidated the mechanism of inducing the orbital polarization in the p symmetric states. We also discuss a simple sum rule connecting the XMCD spectra with the orbital moment in the p symmetric states.

Orbital angular momentum and interpretation of core-absorption magnetic circular dichroism on the band picture in Co-based Heusler alloys CoSn (=Ti, Zr, and Nb)

Yamasaki, Atsushi*; Imada, Shin*; Arai, Ryuji*; Utsunomiya, Hiroshi*; Suga, Shigemasa*; Muro, Takayuki*; Saito, Yuji; Kanomata, Takeshi*; Ishida, Shoji*

Physical Review B, 65(10), p.104410_1 - 104410_6, 2002/03

https://doi.org/10.1103/PhysRevB.65.104410

The magnetic circular dichroism (MCD) of core-level absorption [x-ray absorption spectroscopy (XAS)] spectra in the soft x-ray region has been measured for the ferromagnetic Heusler alloys CoTiSn, CoZrSn, and CoNbSn. The many-peak structures which are clearly observed in the Co 2p-3d XAS-MCD spectra cannot be well explained by atomic multiplet calculations but are better explained by the Co 3d unoccupied states predicted by linear muffin-tin orbital atomic sphere approximation band structure calculations. The MCD spectra show an obvious contribution of the orbital angular momentum component to the magnetic moment in these alloys. The ratio between the orbital angular momentum and spin derived from the MCD spectra varies by more than a factor of 2 within these alloys. The mechanism of this variation is discussed in comparison with the band structure calculations.