James C. Eckert

Professor of Physics

Magnetic device technologies are playing an ever expanding role in our day to day lives. Magnetic storage dates from the 1930’s with the advent of tape recording and the recent high capacity computer hard drives are simply a variation on that same theme. However, the past few years has seen an explosion in the number and type of magnetic devices that have appeared on the scene. Position and location sensors, magnetic switching, and non-volatile computer memory based upon magnetoresistance have all come into common usage within recent years. This was brought about by the discovery of and the exploitation of the effect known as giant magnetoresistance (GMR). The phenomenon of giant magnetoresistance is the large change in electrical resistance of a system when a magnetic field is applied. Samples exhibiting GMR consist of separated regions of ferromagnetic, such as iron or cobalt, and non-magnetic materials. Devices that make use of GMR require a third region of antiferromagnetic material, such as CoO or IrMn, that serve to produce a locking effect, known as exchange coupling, on the direction of the magnetization in one or more of the ferromagnetic regions. This exchange coupling is the central feature in all of these devices and is not well understood. Our research employs electrical transport, magnetization, thermodynamic, and optical measurements to study exchange coupling in thin film magnetic nano-structures with the dual goals of shedding light on the origins of exchange coupling and of enhancing the effect with an eye towards improving and developing magnetic device technologies through the control of the magnetism associated with the spin of the electrons as they move through magnetic structures. This is the budding new field of spintronics.

Research

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