Repeatable photoinduced insulator-to-metal transition in yttrium oxyhydride epitaxial thin films

イットリウム酸水素化物薄膜における繰り返し可能な光誘起金属-絶縁体転位

小松 遊矢*; 清水 亮太*; 佐藤 龍平*; Wilde, M.*; 西尾 和記*; 片瀬 貴義*; 松村 大樹   ; 齋藤 寛之*; 宮内 雅浩*; Adelman, J. R.*; McFadden, R. M.*; Fujimoto, D.*; Ticknor, J. O.*; Stachura, M.*; McKenzie, I.*; Morris, G. D.*; Andrew MacFarlane, W.*; 杉山 純; 福谷 克之*; 常行 真司*; 一杉 太郎*

Komatsu, Yuya*; Shimizu, Ryota*; Sato, Ryuhei*; Wilde, M.*; Nishio, Kazunori*; Katase, Takayoshi*; Matsumura, Daiju; Saito, Hiroyuki*; Miyauchi, Masahiro*; Adelman, J. R.*; McFadden, R. M.*; Fujimoto, D.*; Ticknor, J. O.*; Stachura, M.*; McKenzie, I.*; Morris, G. D.*; Andrew MacFarlane, W.*; Sugiyama, Jun; Fukutani, Katsuyuki*; Tsuneyuki, Shinji*; Hitosugi, Taro*

Here, we demonstrate such a highly repeatable photoinduced insulator-to-metal transition in yttrium oxyhydride (YOH) epitaxial thin films. The temperature () dependence of the electrical resistivity () of the films transforms from insulating to metallic () under ultraviolet laser illumination. The sample is heated (125 C) under an Ar atmosphere to recover its original insulating state. The films recover their original metallic conductivity when subsequently subjected to ultraviolet laser illumination, showing repeatable photoinduced insulator-to-metal transition. First principles calculations show that the itinerant carriers originate from the variations in the charge states of the hydrogen atoms that occupy octahedral interstitial sites. This study indicates that tuning the site occupancy (octahedral/tetrahedral) of the hydrogen atoms exerts a significant effect on the photoresponse of metal hydrides.