Magnetoresistance Dynamics in Superparamagnetic Co-Fe- B Nanodots

Brad Parks; Ahmed Abdelgawad; Thomas Wong; Richard F.L. Evans; Sara A. Majetich

doi:10.1103/PhysRevApplied.13.014063

Magnetoresistance Dynamics in Superparamagnetic Co-Fe- B Nanodots

Brad Parks, Ahmed Abdelgawad, Thomas Wong, Richard F.L. Evans, Sara A. Majetich

Physics

Research output: Contribution to journal › Article › peer-review

Abstract

Individual disk-shaped Co-Fe-B nanodots are driven into a superparamagnetic state by a spin-transfer torque, and their time-dependent magnetoresistance fluctuations are measured as a function of current. A thin layer of oxidation at the edges has a dramatic effect on the magnetization dynamics. A combination of experimental results and atomistic spin simulations shows that pinning to oxide grains can reduce the likelihood that fluctuations lead to reversal, and can even change the easy-axis direction. Exchange-bias loop shifts and training effects are observed even at room temperature after brief exposure to small fields. The results have implications for studies of core-shell nanoparticles and small magnetic tunnel junctions and spin-torque oscillators.

Original language	English
Article number	014063
Journal	Physical Review Applied
Volume	13
Issue number	1
DOIs	https://doi.org/10.1103/PhysRevApplied.13.014063
Publication status	Published - 30 Jan 2020

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10.1103/PhysRevApplied.13.014063

PhysRevApplied.13.014063
© 2020 American Physical Society. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details
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AU - Evans, Richard F.L.

AU - Majetich, Sara A.

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Magnetoresistance Dynamics in Superparamagnetic Co-Fe- B Nanodots

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