Magnetic Nanostructures; Confinement, Proximity and Induced Phenomena

CIC nanoGUNE Seminars

Speaker

Ivan K. Schuller, Physics Department, UCSD, La Jolla, California, USA

When

2011/11/29
13:00

Place

nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian

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Magnetic nanostructures are receiving increasing attention in recent years, motivated by the interesting phenomena when the physical size becomes comparable to relevant magnetic length scales. In addition a number of important potential applications in the sensors and storage industries have emerged. When magnetic nanostructures are in contact (“proximity”) with other dissimilar magnetic materials and because their magnetic fields extend considerably outside the physical structure they are very susceptible to interactions with the surrounding environment. A particularly interesting situation is one in which a ferromagnetic nanostructure is in contact with an antiferromagnetic substrate. In this "exchange biased" proximity configuration, a variety of unusual phenomena arise; the reversal mode of the ferromagnet changes considerably, the superparamagnetic transition temperature is affected and there is a noticeable change in the microscopic spin configuration. I will describe a series of experiments in which we studied these phenomena in nanostructured ferromagnets prepared by electron beam lithography and self-assembly. These experiments include magnetotransport, magnetization, Magneto-Optic Kerr effect, neutron and synchrotron scattering, and ultrafast pump probe. An attempt to arrive at a universal understanding to many confusing issues in the field will be presented. Work supported by the US Department of Energy, US Air Force Office of Scientific Research