Nanomagnetism

My research explores lateral confinement and coupling effects in nanomagnets through both experimental investigations and numerical modeling. In addition to being an exciting subject of study from a fundamental perspective, nanomagnets are also important for the advancement of technology, for example, in spintronics devices, storage media, and for medical applications. My present work focuses on the magnetization reversal and spin excitations of patterned magnetic elements. For details on magnetics research at CSU see the Magnetic Materials and Applied Magnetics Laboaratory (MMAML) website.

Selected Publications

• Liu, H. J., Riley, G. A., and Buchanan, K. S. Detection of directly-excited magnetostatic backward volume wave in Permalloy microstrips, IEEE Magnetics Letters, PP (99), 1 (2015) (in press, available online).
• Riley, G., Haldar, A., Liu, H. J., Asmat-Uceda, M., and Buchanan, K. S., Observation of the dynamic modes of a magnetic antivortex using Brillouin light scattering, Physical Review B 92, 064423 (2015).
• Asmat-Uceda, M., Li, L., Shaw, B., Haldar, A., and Buchanan, K. S., The role of shape anisotropy in the stabilization of magnetic antivortices in pound-key like structures, J. of Appl. Phys. 117, 173902 (2015).
• Asmat-Uceda, M., Cheng, X., Wang, X., Keavney, D., Clarke, D., Tchernyshyov, O., and Buchanan, K. S., A comparison of numerical simulations and analytical theory of the dynamics of interacting magnetic vortices, J. of Appl. Phys. 117, 123916 (2015).
• Gilbert, D. A., Ye, L., Varea, A., Agramunt-Puig, S., del Valle, N., Navau, C., López-Barbera, J. F., Buchanan, K. S., Hoffmann, A., Sánchez, A., Sort, J., Liu, K., and Nogués, J., New reversal mode in exchange coupled antiferromagnetic/ferromagnetic disks: Distorted viscous vortex, Nanoscale 7, 9878 – 9885 (2015).
• Wang, X., Keavney, D., Asmat-Uceda, M., Buchanan, K. S., A. Melikyan, Cheng, X., Time-resolved PEEM imaging of mode coupling between three interacting magnetic vortices, Appl. Phys. Lett. 105, 102408 (2014).
• Haldar, A. and Buchanan, K. S., Controlled generation of isolated magnetic antivortices in pound-key-like patterned micro-structures, Appl. Phys. Lett. 102, 112401 (2013).
• Pollard, S. D., Huang, L., Buchanan, K. S., Arena, D. A. and Zhu, Y., Direct Dynamic Imaging of Non-Adiabatic Spin Torque Effects, Nature Communications 3, 1028(2012); doi: 10.1038/ncomms2025.
• Matthieu, C., Liu, H. J., Buchanan, K. S., and Inturi, V. R., Volume Exchange in Soft FeCo Films of High Magnetization, J. Appl. Phys. 111, 07A306 (2012).
• Buchanan, K. S., Grimsditch, M., Fradin, F. Y., Bader, S. D., and Novosad, V. Driven dynamic mode-splitting of the magnetic vortex translational resonance. Phys. Rev. Lett. 99, 267201 (2007). (Selected for the January 2008 issue of the Virtual Journal of Nanoscale Science & Technology.)
• Bader, S. D., Buchanan, K. S., Chung, S. -H., Guslienko, K. Yu., Hoffmann, A., Ji, Y., and Novosad, V. Issues in nanomagnetism. Superlattices and Microstructures 41, 72-80 (2007).
• Buchanan, K. S., Roy, P. E., Grimsditch, M., Fradin, F. Y., Guslienko, K. Yu., Bader, S. D., and Novosad, V. Magnetic field tunability of the vortex translational mode in micron-sized permalloy ellipses. Phys. Rev. B 74, 064404 (2006).
• Sort, J., Buchanan, K. S., Novosad, V., Hoffmann, A., Salazar-Alvarez, G., Baro, M. D., Dieny, B., and Nogues, J. Imprinting vortices into antiferromagnets. Phys. Rev. Lett. 97, 067201 (2006).
• Buchanan, K. S., Roy, P. E., Grimsditch, M., Fradin, F. Y., Guslienko, K. Yu., Bader, S. D., and Novosad, V. Soliton pair dynamics in patterned ferromagnetic ellipses. Nature Physics 1, 172-176 (2005).
• Novosad, V., Fradin, F. Y., Roy, P. E., Buchanan, K. S., Guslienko, K. Yu., and Bader, S. D. Magnetic Vortex Resonance in Patterned Ferromagnetic Dots, Phys. Rev. B 72, 024455 (2005). (Selected for the August 2005 issue of the Virtual Journal of Nanoscale Science & Technology.)
• Buchanan, K. S., Zhu, X., Meldrum, A., and Freeman, M. R. Ultrafast dynamics of a ferromagnetic nanocomposite. Nano Letters 5, 383 387 (2005).