Exchange anisotropy pinning of a standing spin-wave mode

Magaraggia, R., Kennewell, K., Kostylev, M., Stamps, R.L. , Ali, M., Greig, D., Hickey, B.J. and Marrows, C.H. (2011) Exchange anisotropy pinning of a standing spin-wave mode. Physical Review B, 84(21), 054405. (doi: 10.1103/PhysRevB.83.054405)

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Publisher's URL: http://link.aps.org/doi/10.1103/PhysRevB.83.054405

Abstract

Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin-wave thickness mode in Ni<sub>80</sub>Fe<sub>20</sub>/Ir<sub>25</sub>Mn<sub>75</sub> exchange-biased bilayers was studied for a range of Ir<sub>25</sub>Mn<sub>75</sub> thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique “fingerprint” of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet-antiferromagnet interface anisotropy. Thermal effects are studied for ultrathin antiferromagnetic Ir<sub>25</sub>Mn<sub>75</sub> thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Stamps, Professor Robert and Magaraggia, Mr Rhet
Authors: Magaraggia, R., Kennewell, K., Kostylev, M., Stamps, R.L., Ali, M., Greig, D., Hickey, B.J., and Marrows, C.H.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review B
ISSN:1098-0121
ISSN (Online):1550-235X

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