Controllable Positive Exchange Bias via Redox-Driven Oxygen Migration

Published

March 21, 2016

Author(s)

Dustin A. Gilbert, Justin Olamit, Randy K. Dumas, Brian J. Kirby, Alexander J. Grutter, Brian B. Maranville, Elke Arenholz, Julie A. Borchers, Kai Liu

Abstract

We have observed oxygen migration across buried interfaces in Gd^xdx^Fe_1-x/NiCoO films, which leads to tunable positive exchange bias over a relatively small cooling field range of 300 mT. The tunability is shown to be the result of an interfacial layer of elemental NiCo, a few nanometers in thickness, substantially thicker than expected from uncompensated NiCoO moments. This interface layer is attributed to chemical reduction of the NiCoO by the Gd. Increasing the Gd:Fe ration suppresses the tunability; the major hysteresis loop is always positively biased at large Gd concentrations (>53 at.%). The reversal behavior of each layer is distinguished directly by element-specific X-ray magnetic circular dichroism spectroscopy, and the depth profile is identified by polarized neutron reflectometry. These results demonstrate a new and effective path to control the interfacial exchange coupling in metal/oxide heterostructures.

Citation

Nature Communications

Volume

7

Pub Type

Journals

Download Paper

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Keywords

Magnetism, redox, PNR, XMCD, Interface, exchange bias

Citation

Gilbert, D. , Olamit, J. , , R. , Kirby, B. , Grutter, A. , , B. , Arenholz, E. , Borchers, J. and Liu, K. (2016), Controllable Positive Exchange Bias via Redox-Driven Oxygen Migration, Nature Communications, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=919678 (Accessed October 27, 2025)