Atomic Engineering of Spin Valves Using Ag as a Surfactant

Published

June 1, 2001

Author(s)

D X. Yang, B Shashishekar, H D. Chopra, P J. Chen, William F. Egelhoff Jr.

Abstract

In this study, de magnetron sputtered NiO (50 nm)/Co (2.5 nm)/Cu (1.5 nm)/Co(3.0 nm) bottom spin valves were studied with and without Ag as a surfactant. At Cu spacer thickness of 1.5 nm, a strong positive coupling >13.92 kA/m (>175 Oe) between NiO-pinned and free Co layers leads to a negligible giant magnetoresistance (GMR) efect (< 0.7 %) in Ag-free samples. In addition to positive oscillatory exchange coupling in the proximity of first minima of oscillatory exchange at 1.5 nm Cu thickness, coupling due to pinholes exists in the Ag-free spin valves. In contrast, when the spin valves are deposited in the presence of approximately equal to} 0.7 monolayers (MLs) of surfactant Ag, the coupling is sufficiently reduced, 5.65 kA/m (80 Oe), to result in a moderate GMR effect (8.5 %); this represents more than an order of magnitude increase in GMR in comparison to Ag-free samples. In-situ x-ray photoelectron spectroscopy (XPS) shows that the large and highly mobile Ag atoms float out to the surface during successive growth of Co and Cu layers. Detailed TEM studies show that surfactant Ag leaves behind smooth interfaces without pinholes. These observations explain contribution to net coupling from various sources, the observed decrease in positive coupling, and an order of magnitude increase in GRM in Ag-containing samples. The use of surfactants also illustrates their efficacy in favorably altering the magnetic characteristics of GMR spin valves, and their potential use in other magnetoelectronics devices.

Citation

Journal of Applied Physics

Volume

89

Issue

No. 11

Pub Type

Journals

Keywords

giant magnetoresistance, silver, spin valves, surfactant

Citation

Yang, D. , Shashishekar, B. , Chopra, H. , Chen, P. and Egelhoff Jr., W. (2001), Atomic Engineering of Spin Valves Using Ag as a Surfactant, Journal of Applied Physics (Accessed July 27, 2024)