Room-temperature local ferromagnetism and its nanoscale expansion in the ferromagnetic semiconductor Ge 1–x Fe x
Yuki K. Wakabayashi,Shoya Sakamoto,Yukiharu Takeda,K. Ishigami,Y. Takahashi,Yuji Saitoh,Hiroshi Yamagami,Hiroshi Yamagami,Atsushi Fujimori,Masaaki Tanaka,Shinobu Ohya +10 more
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TLDR
It is found that nanoscale local ferromagnetic regions, which are formed through ferrom electromagnetic exchange interactions in the high-Fe-content regions of the GeFe films, exist even at room temperature, well above the Curie temperature of 20–100 K.Abstract:
We investigate the local electronic structure and magnetic properties of the group-IV-based ferromagnetic semiconductor, Ge1−xFex (GeFe), using soft X-ray magnetic circular dichroism. Our results show that the doped Fe 3d electrons are strongly hybridized with the Ge 4p states, and have a large orbital magnetic moment relative to the spin magnetic moment; i.e., morb/mspin ≈ 0.1. We find that nanoscale local ferromagnetic regions, which are formed through ferromagnetic exchange interactions in the high-Fe-content regions of the GeFe films, exist even at room temperature, well above the Curie temperature of 20–100 K. We observe the intriguing nanoscale expansion of the local ferromagnetic regions with decreasing temperature, followed by a transition of the entire film into a ferromagnetic state at the Curie temperature.read more
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Electronic structure of the high- T C ferromagnetic semiconductor (Ga,Fe)Sb: X-ray magnetic circular dichroism and resonance photoemission spectroscopy studies
Shoya Sakamoto,Nguyen Thanh Tu,Yukiharu Takeda,Shin-ichi Fujimori,Pham Nam Hai,Pham Nam Hai,Le Duc Anh,Yuki K. Wakabayashi,Goro Shibata,Masafumi Horio,Keisuke Ikeda,Yuji Saitoh,Hiroshi Yamagami,Hiroshi Yamagami,Masaaki Tanaka,Atsushi Fujimori +15 more
TL;DR: In this article, the electronic structure and magnetism of the ferromagnetic semiconductor (Ga,Fe)Sb, whose Curie temperature can exceed room temperature, were investigated by means of x-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), and resonance photo-emission spectra (RPES).
Journal ArticleDOI
First-principles calculations on the origin of ferromagnetism in transition-metal doped Ge
TL;DR: In this paper, the authors investigated the electronic structures, structural stabilities, magnetic exchange coupling constants, and Curie temperature of Ge-based dilute magnetic semiconductors and clarified origins of the ferromagnetism, on the basis of density functional theory calculations.
Journal ArticleDOI
Cation distribution and magnetic properties in ultrathin ( N i 1 – x C o x ) F e 2 O 4 ( x = 0 – 1 ) layers on Si(111) studied by soft x-ray magnetic circular dichroism
Yuki K. Wakabayashi,Yosuke Nonaka,Yukiharu Takeda,Shoya Sakamoto,Keisuke Ikeda,Zhendong Chi,Goro Shibata,Arata Tanaka,Yuji Saitoh,Hiroshi Yamagami,Masaaki Tanaka,Atsushi Fujimori,Ryosho Nakane +12 more
Journal ArticleDOI
Systematic study of the electronic structure and the magnetic properties of a few-nm-thick epitaxial (Ni1-xCox)Fe2O4(x = 0 - 1) layers grown on Al2O3(111)/Si(111) using soft X-ray magnetic circular dichroism: Effects of cation distribution
Yuki K. Wakabayashi,Yuki K. Wakabayashi,Yosuke Nonaka,Yukiharu Takeda,Shoya Sakamoto,Keisuke Ikeda,Zhendong Chi,Goro Shibata,Arata Tanaka,Yuji Saitoh,Hiroshi Yamagami,Masaaki Tanaka,Atsushi Fujimori,Ryosho Nakane +13 more
TL;DR: Wakabayasi et al. as mentioned in this paper studied the electronic structure and magnetic properties of epitaxial (Ni1-xCox)Fe2O4(111) layers (x = 0 - 1) with thicknesses d = 1.7 - 5.2 nm, and achieved a high value of inversion parameter y, which is the inverse-to-normal spinel-structure ratio.
References
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