Thickness-dependent ferromagnetic metal to paramagnetic insulator transition in LaSrMnO thin films studied by X-ray magnetic circular dichroism

LaSrMnO薄膜における膜厚に依存した強磁性金属-常磁性絶縁体転移のX線吸収磁気円二色性測定による研究

芝田 悟朗*; 吉松 公平*; 坂井 延寿*; Singh, V. R.*; Verma, V.*; 石上 啓介*; 原野 貴幸*; 門野 利治*; 竹田 幸治   ; 岡根 哲夫  ; 斎藤 祐児  ; 山上 浩志; 澤 彰仁*; 組頭 広志*; 尾嶋 正治*; 小出 常晴*; 藤森 淳

Shibata, Goro*; Yoshimatsu, Kohei*; Sakai, Enju*; Singh, V. R.*; Verma, V.*; Ishigami, Keisuke*; Harano, Takayuki*; Kadono, Toshiharu*; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Yamagami, Hiroshi; Sawa, Akihito*; Kumigashira, Hiroshi*; Oshima, Masaharu*; Koide, Tsuneharu*; Fujimori, Atsushi

Metallic transition-metal oxides undergo a metal-to-insulator transition (MIT) as the film thickness decreases across a critical thickness of several monolayers (MLs), but its driving mechanism remains controversial. We have studied the thickness-dependent MIT of the ferromagnetic metal LaSrMnO by X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The results suggest that the ferromagnetic phase gradually and most likely inhomogeneously turns into the paramagnetic phase and both phases abruptly become insulating at the critical thickness.