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Higher order perpendicular magnetic anisotropy in ultra-thin Co60Fe20B20 layers and the observation of an easy cone state.

Published

Author(s)

Justin M. Shaw, Hans T. Nembach, Mathias A. Weiler, Martin A. Schoen, Thomas J. Silva, Jonathan Z. Sun, Daniel C. Worledge

Abstract

We used broadband ferromagnetic resonance (FMR) spectroscopy to measure the second and forth order perpendicular magnetic anisotropies in Ta/ Co60Fe20B20/MgO layers over a thickness range of 0.8-5 nm. For a thickness greater than 1.0 nm, the easy axis is in the plane of the film, but when the thickness is less than 1.0 nm, the easy axis is found to be directed perpendicular to the surface. However, due to the presence of a strong higher order perpendicular anisotropy, an easy cone state is found when the thickness of the CoFeB layer is 1.0 nm. Angular dependent FMR measurements verify the presence of the easy cone state. Analysis of the spectroscopic g-factor for the in-plane and out-of-plane geometries also indicates a dramatic change in structure at approximately 1.0 nm thickness.
Citation
Applied Physics Letters
Volume
6

Keywords

Ferromagnetic resonance, spintronics, perpendicular anisotropy, magnetic tunnel junction

Citation

Shaw, J. , Nembach, H. , Weiler, M. , Schoen, M. , Silva, T. , Sun, J. and Worledge, D. (2015), Higher order perpendicular magnetic anisotropy in ultra-thin Co60Fe20B20 layers and the observation of an easy cone state., Applied Physics Letters (Accessed April 18, 2024)
Created June 1, 2015, Updated February 20, 2017