• Ohya, Shinobu
• Tanaka, Masaaki
• Wakabayashi, Yuki K.
• Saitoh, Yuji
• Fujimori, Atsushi
• Yamagami, Hiroshi
• Takahashi, Yukio
• Sakamoto, Shoya
• Takeda, Yuki-Haru
• Ishigami, Keisuke

Abstract

<jats:title>Abstract</jats:title><jats:p>We investigate the local electronic structure and magnetic properties of the group-IV-based ferromagnetic semiconductor, Ge<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>Fe<jats:sub><jats:italic>x</jats:italic></jats:sub> (GeFe), using soft X-ray magnetic circular dichroism. Our results show that the doped Fe 3<jats:italic>d</jats:italic> electrons are strongly hybridized with the Ge 4<jats:italic>p</jats:italic> states, and have a large orbital magnetic moment relative to the spin magnetic moment; i.e., <jats:italic>m</jats:italic><jats:sub>orb</jats:sub>/<jats:italic>m</jats:italic><jats:sub>spin</jats:sub> ≈ 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.</jats:p>

Topics

• semiconductor
• Curie temperature