X-ray magnetic circular dichroism in (Ge,Mn) compounds: Experiments and modeling

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• 作者：Samuel Tardif ; Andrey Titov ; Emmanuel Arras ; Ivetta Slipukhina ; El-K茅bir Hlil ; Salia Cherifi ; Yves Joly ; Matthieu Jamet ; Andr茅 Barski ; Jo毛l Cibert ; Erkin Kulatov ; Yurii A. Uspenskii ; Pascal Pochet
• 关键词：(Ge ; Mn) ; XAS ; XMCD
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：March, 2014
• 年：2014
• 卷：354
• 期：Complete
• 页码：151-158
• 全文大小：745 K

文摘

X-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra at the L_2,3 edges of Mn in (Ge,Mn) compounds have been measured and are compared to the results of first principles calculation. Early ab initio studies show that the Density Functional Theory (DFT) can very well describe the valence band electronic properties but fails to reproduce a characteristic change of sign in the L₃ XMCD spectrum of Mn in Ge₃Mn₅, which is observed in experiments. In this work we demonstrate that this disagreement is partially related to an underestimation of the exchange splitting of Mn 2p core states within the local density approximation. It is shown that the change in sign experimentally observed is reproduced if the exchange splitting is accurately calculated within the Hartree-Fock approximation, while the final states can be still described by the DFT. This approach is further used to calculate the XMCD in different (Ge,Mn) compounds. It demonstrates that the agreement between experimental and theoretical spectra can be improved by combining state of the art calculations for the core and valence states respectively.