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A New Spin on Efficiency

What do baseball and computers have in common? According to Dr. Jian Liu of the University of Tennessee’s department of physics, the answer is spin or, more specifically, spin-orbit coupling.

Spin-orbit coupling is the interaction that occurs between an object’s spin and its motion or trajectory. With baseball this is illustrated in pitching. A pitcher is always propelling the ball forward toward the catcher. However, the spin he applies to the ball as it makes its way to home plate will affect the way the ball behaves as it travels. Spin applied in one direction can result in a curveball, while when applied in another direction can yield a screwball.

In Liu’s Joint Directed Research Development (JDRD) project, spin-orbit coupling presents a new way to tackle speed and efficiency in computers.

“In computers, the basic idea is you switch between two states, ‘0’ and ‘1’. How fast a computer can go or how much data it can store depends on how well it can switch between these two states,” said Liu.

Magnetic materials are commonly used for this and an alternating magnetic field is applied to them to induce the changing state by flipping the direction in which the electrons are spinning within the materials. According to Liu, this method requires a great deal of electric current and is very energy consuming as a result. The goal of his JDRD project is to increase the speed with which these changes are made while using less energy.

“What we’re trying to do here is build a structure where the magnetic property and the electric property would have an intrinsic correlation, and the concept behind all of this is to utilize the spin-orbit coupling,” said Liu.

Liu’s work could lead to major advances in electronics technology. Hard drives could store more, devices could perform faster on less energy and entirely new devices could be created.

Liu’s partner at Oak Ridge National Laboratory (ORNL), Dr. Michael Fitzsimmons, is developing a sample environment of polarized neutron reflectometry (PNR). This environment is dedicated to investigating interfacial structures with controls over magnetic and electric fields and Fitzsimmons will use it to characterize the material the JDRD team is creating for Liu’s research.

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