Nanomagnetic Playground: Magneto-Ionics and HAMR Media
The coming end of Moore’s law underscores the urgency of developing highly energy-efficient nanoelectronics. Spintronics offers an exciting new paradigm to address this grand challenge. In this talk I will first discuss magneto-ionic control of metal/oxide heterostructures, which offers a highly effective means to tailor material properties via modification of the interfacial characteristics. Currently, direct observation of ionic motion under buried interfaces and demonstration of its correlation with the physical properties have been challenging. Utilizing the strong oxygen affinity of gadolinium, we design a model system of GdFe/NiCoO bilayer films, where the oxygen migration is observed and manifested in a controlled positive exchange bias . We further show that the magnetoelectric coupling moderated by voltage-driven oxygen migration extends beyond the interface region in relatively thick AlOx/GdOx/Co(15 nm) films . In the second part I will discuss a magnetometry-based order parameter to characterize high anisotropy L10 FePt films that are prototype media for the emerging heat-assisted magnetic recording (HAMR) technology. We also show an extremely sensitive magnetic yoking effect and tunable interactions in FePt based hard/soft bilayers mediated by the soft layer . These findings demonstrate an effective approach to design and control magnetic interactions in wide varieties of magnetic nanostructures and devices.
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3. D. A. Gilbert, et al, Sci. Rep. 6, 32842 (2016).