[11p-M101-15~21] 10.3 Spin devices, magnetic memories and storages

▼ [11p-M101-18] Giant MR Ratio by Using Metastable bcc-Cu Spacer Layer in Epitaxial Current In-Plane Giant Magnetoresistance Devices

〇(M2)Kresna Bondan Fathoni^1,2, Yuya Sakuraba¹, Taisuke Sasaki¹, Yoshio Miura¹, Jinwon Jung¹, Tomoya Nakatani¹, Kazuhiro Hono¹ (1.NIMS, 2.Univ. of Tsukuba)

Keywords:giant magnetoresistance, sensor, bcc Cu

In current in-plane giant magnetoresistance (CIP-GMR), large value of magnetoresistance (MR) ratio is necessary for various sensor applications. It is well known that good lattice and band matching is necessary to obtain large MR ratio. We investigated epitaxial bcc Co_1-xFe_x-based CIP-GMR spin valves with thin Cu spacer. The stacking of MgO subs./Co_1-xFe_x/Cu/Co_1-xFe_x/IrMn/Ta were deposited by sputtering with x = 10, 25, 50, 67 and 100. The largest observed MR ratio of 26% in Co₅₀Fe₅₀. Then we use Co₅₀Fe₅₀ for new design of MgO subs./Co₅₀Fe₅₀/Cu/Co₅₀Fe₅₀/MgO to introduce a specular reflection from MgO to enhance MR ratio. As a result, we observed giant MR of 40% which is the highest MR in trilayer CIP-GMR ever reported. Our TEM analysis confirmed Co₅₀Fe₅₀ and Cu layers coherently connected without any dislocation due to the formation of bcc Cu spacer. Our first principle calculation confirmed that the good band matching of bcc Cu and Co₅₀Fe₅₀ is the origin for observed giant MR ratio.