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Switching to Spintronics


Conceptual illustration of how magnetism is reversed (see compass) by the application of an electric field (blue dots) applied across gold capacitors.

Researchers at the Lawrence Berkeley National Laboratory and Cornell University used an electric field to reverse the magnetization direction in a multiferroic spintronic device at room temperature.

Credit: John Heron/Cornell

Researchers at the Lawrence Berkeley National Laboratory and Cornell University have successfully used an electric field to reverse the magnetization direction in a multiferroic spintronic device at room temperature. This suggests a new approach to spintronics and smaller, faster, and less expensive ways of storing and processing data.

Berkeley Lab's Ramamoorthy Ramesh says his team used "a multi-step switching process to demonstrate energy-efficient control of a spintronic device."

In earlier research, Ramesh's team had discovered a two-step switching process that relied on ferroelectric polarization and the rotation of the oxygen octahedral. "The two-step switching process is key as it allows the octahedral rotation to couple to the polarization," says Cornell University's John Heron. "The oxygen octahedral rotation is also critical because it is the mechanism responsible for the ferromagnetism in bismuth ferrite."

Ramesh, Heron, and their co-researchers used heterostructures of bismuth ferrite and cobalt iron to form a spin-valve, or a spintronic device consisting of a non-magnetic material sandwiched between two ferromagnets whose electrical resistance can be readily changed. X-ray magnetic circular dichroism photoemission electron microscopy images revealed a correlation between magnetization switching and the switching from high-to-low electrical resistance in the spin-valve.

From Berkeley Lab News Center
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