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arXiv · 1505.01402

Magnetization Process of the n-type Ferromagnetic Semiconductor (In,Fe)As:Be Studied by X-ray Magnetic Circular Dichroism

Shoya Sakamoto·Le Duc Anh·Pham Nam Hai·Goro Shibata·Yukiharu Takeda·Masaki Kobayashi·Yukio Takahashi·Tsuneharu Koide·Masaaki Tanaka·Atsushi Fujimori
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Abstract

In order to investigate the mechanism of ferromagnetic ordering in the new n-type magnetic semiconductor (In,Fe)As co-doped with Be, we have performed X-ray absorption spectroscopy and X-ray magnetic circular dichroism (XMCD) studies of ferromagnetic and paramagnetic samples. The spectral line shapes suggest that the ferromagnetism is intrinsic originating from Fe atoms incorporated into the Zinc-blende-type InAs lattice. The magnetization curves of Fe measured by XMCD were well reproduced by the superposition of a Langevin function representing superparamagnetic (SPM) behavior of nano-scale ferromagnetic domains and a T-linear function representing Curie-Weiss paramagnetism even much above the Curie temperatures. The data at 20 K showed a deviation from the Langevin behavior, suggesting a gradual establishment of macroscopic ferromagnetism on lowering temperature. The existence of nano-scale ferromagnetic domains indicated by the SPM behavior suggests spatial fluctuations of Fe concentration on the nano-scale.

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Shoya Sakamoto, Le Duc Anh, Pham Nam Hai, Goro Shibata, Yukiharu Takeda, Masaki Kobayashi, Yukio Takahashi, Tsuneharu Koide, Masaaki Tanaka, Atsushi Fujimori. 2015-05-06. Magnetization Process of the n-type Ferromagnetic Semiconductor (In,Fe)As:Be Studied by X-ray Magnetic Circular Dichroism. https://doi.org/10.1103/physrevb.93.035203

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