Possible existence of magnetic polaron in nearly ferromagnetic semiconductor -US

強磁性近傍にある半導体-USにおける磁気ポーラロンの存在の可能性

池田 修悟*; 酒井 宏典   ; 立岩 尚之   ; 松田 達磨; 青木 大*; 本間 佳哉*; 山本 悦嗣  ; 中村 彰夫; 塩川 佳伸*; 太田 有基*; 杉山 清寛*; 萩原 政幸*; 金道 浩一*; 松林 和幸*; 辺土 正人*; 上床 美也*; 芳賀 芳範   ; 大貫 惇睦

Ikeda, Shugo*; Sakai, Hironori; Tateiwa, Naoyuki; Matsuda, Tatsuma; Aoki, Dai*; Homma, Yoshiya*; Yamamoto, Etsuji; Nakamura, Akio; Shiokawa, Yoshinobu*; Ota, Yuki*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; Kindo, Koichi*; Matsubayashi, Kazuyuki*; Hedo, Masato*; Uwatoko, Yoshiya*; Haga, Yoshinori; Onuki, Yoshichika

We studied the magnetic properties of a paramagnet -US with the orthorhombic crystal structure by measuring the magnetization, magnetic susceptibility, specific heat and electrical resistivity under magnetic field and pressure. The 5-crystalline electric field (CEF) scheme was determined from the experimental results The insulating resistivity is drastically changed to a metallic one under high pressure 8 GPa similar to that of the semimetallic Ising-type ferromagnet UTeS with the Curie temperature =87 K. From these experimental results, it was concluded that -US is in the vicinity of the ferromagnetic ordering at ambient pressure. The anomalous magnetization was analyzed on the basis of the ferromagnetic cluster and discussed from a viewpoint of the magnetic polaron.