Enhancement of spin–orbit interaction of Cu thin films by oxidation treatment

We report the strength of spin-orbit interaction (SOI) and spin relaxation mechanisms for Cu oxide (CuOx) thin films with different oxidation procedures. The CuOx depth profiles are characterized by X-ray photoelectron spectroscopy. The spin-related properties are investigated on the basis of a quantum interference effect. The strength of SOI is more than four times larger for naturally oxidized CuOx films than for CuOx films fabricated by oxygen reactive sputtering. In addition, the spin relaxation process for naturally oxidized CuOx films is governed by both the D'yakonov-Perel' mechanism and the Elliott-Yafet mechanism, whereas that for CuOx films fabricated by oxygen reactive sputtering is dominated by the Elliott-Yafet mechanism. (C) 2018 The Japan Society of Applied Physics