Exchange enhancement and thermal anneal in Mn/sub 76/Ir/sub 24/ bottom-pinned spin valves

Haohua, L., Freitas, P.P., Zhenjun, W., Sousa, J.B., Gogol, P. and Chapman, J.N. (2001) Exchange enhancement and thermal anneal in Mn/sub 76/Ir/sub 24/ bottom-pinned spin valves. Journal of Applied Physics, 89(11), 6904 -6906. (doi: 10.1063/1.1354581)

Abstract

Exchange enhancement through thermal anneal in bottom-pinned Mn/sub 76/Ir/sub 24/ spin valves is investigated. Samples were fabricated by ion beam deposition (IBD), post-annealed in vacuum (10/sup -6/ Torr) at 270 degrees C for 10 min, then cooled in a 3 kOe applied field. For a bilayer structure, glass/Ta 40 AA/NiFe 30 AA/MnIr 60 AA/CoFe 25 AA/Ta 40 AA, the exchange field (H/sub ex/) reaches 1148 Oe (J/sub ex/=0.4 erg/cm/sup 2/) after anneal. X-ray diffraction (XRD) analysis shows strong enhancement of [111] texture upon anneal, while grain size obtained from XRD and transmission electron microscopy for as-deposited and annealed states shows no major change. With increasing MnIr thickness, the exchange field decreases, and blocking temperature (T/sub b/) increases, reaching 295 degrees C for t/sub MnIr/=180 AA. Spin valves built with the same exchange bilayer (Ta 20 AA/NiFe 30 AA/MnIr 60 AA/CoFe 25 AA/Cu 22 AA/CoFe 20 AA/NiFe 40 AA/Ta 40 AA) show H/sub ex/=855 Oe (J/sub ex/=0.3 erg/cm/sup 2/) and magnetoresistance (MR)=7.1%. The incorporation of nano-oxide layers in spin valves increases the MR signal to 11%. No signal degradation is found in these specular structures for anneals up to 310 degrees C.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: UNSPECIFIED
• Authors: Haohua, L., Freitas, P.P., Zhenjun, W., Sousa, J.B., Gogol, P., and Chapman, J.N.
• Subjects: Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Journal of Applied Physics
• ISSN: 0021-8979