Controlling materials at the nanoscale with ion migration

Ionic crystals play a crucial role in nearly every field of material science, ranging from well-established functional materials to highly exotic, cutting-edge research materials. In ionic crystals, bonding between the (inter)metallic atoms and ions, such as oxygen or nitrogen, gives rise to interactions which then manifest new and interesting behaviors. Control over the ion distribution thus provides a powerful mechanism to tune the properties of these materials at an atomic level. Furthermore, the very nature of ionic crystals - with net charges on the constituent atoms - unlocks the potential for electric field control, and thus is attractive for low-power device applications. In this talk, I will introduce the emerging field of magneto-ionics, in which the magnetic properties of materials are tuned by controlling the ionic distributions using both electric field and chemical control mechanisms. Highlighted in this work, I demonstrate control over magnetic interfaces [1] and magnetic films with bulk-like properties [2]. I then show that, in similar systems, the magnetism can be directly controlled using electric fields through the magneto-ionic effect [3]. Neutron scattering and x-ray spectroscopy are demonstrated as optimal tools for probing the oxygen migration and the unexpected magnetic ramifications. These works together present significant opportunities for a new class of device technologies.

[1] Gilbert et al., Nature Commun. 7, 11050 (2016).
[2] Grutter et al., Appl. Phys. Lett. 108, 082405 (2016).
[3] Gilbert et al., Nature Commun. 7, 12264 (2016).

Bio:
Dustin Gilbert is a research physicist at the United States' National Institute of Standards and Technology. He received his B.S. from the University of California at Santa Cruz in Physics, and an M.S. and Ph.D. from the University of California at Davis, also in Physics. He has been active in the area of nanoscale materials with an emphasis on magnetism, including high-anisotropy materials, patterned nanostructures, chiral spin textures, and interface coupled composites. His current research has leveraged the unique capabilities of neutron scattering and synchrotron X-rays together to advance the understanding of new emergent fields, including magneto-ionics, skyrmions, and topological insulators.