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Spin Dynamics in Inhomogeneously Magnetized Systems - Teruo Ono: IEEE Magnetics Society Distinguished Lecture 2016

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Professor Teruo Ono, PhD, aInstitute for Chemical Research at the Division of Materials Chemistry of Kyoto University, presents a distinguished lecture addressing his motivation in working with magnetization and spintronics. Professor Ono offers examples of real-time observation of the domain wall, measuring magnetic vortex, and requirements for practical applications. 

Worldwide efforts are underway to create revolutionary and energy-efficient data storage technology such as magnetic random-access memory (MRAM). An understanding of spin dynamics in inhomogeneously magnetized systems is indispensable for further development of nanoscale magnetic memory. This lecture provides a clear picture of inhomogeneously magnetized systems, such as magnetic nanowires with domain walls and disks with magnetic vortices, and presents not only technological developments and key achievements but also the unsolved puzzles and challenges that stimulate researchers in the field. First, the basic concept of an inhomogeneously magnetized system is described by introducing a magnetic vortex structure in a magnetic disk.

A magnetic domain wall in a magnetic nanowire is also provided as a typical example. The magnetic field-driven dynamics of these inhomogeneously magnetized systems are described to illustrate their uniqueness. Second, electric-current-induced dynamics of magnetic vortices and domain walls are described. One can flip the core magnetization in a magnetic vortex using electrical current excitation, and move a domain wall by current injection into a wire. The next part focuses on the applications of current-induced magnetization dynamics in devices. The basic operations of two kinds of magnetic memoriesmagnetic vortex core memory and magnetic domain wall memoryare demonstrated.

The lecture describes not only the current understanding about inhomogeneously magnetized systems, but also unexpected features that have emerged. It concludes with prospects for future developments.