Proton Pump...

Magneto-ionic switching based on hydrogen accumulation at the metallic ferromagnet/nonmagnetic heavy metal interface. Courtesy: G Beach

Topics: Electrical Engineering, Electromagnetism, Materials Science, Semiconductor Technology, Spintronics

Researchers at the Massachusetts Institute of Technology say they have discovered a new way to electrically control magnetism using a gate voltage that could be applied to a wide variety of magnetic materials, including oxides and metals. The “magneto-ionic” technique, which involves reversibly inserting and removing protons into the material structures, could help advance the field of spintronics (a technology that exploits the spin of the electron rather than its electrical charge) for the post CMOS-world.

Complementary metal-oxide semiconductor (CMOS) technologies are reaching the end of their road map and scientists are looking for alternatives to silicon microchips. Spintronics devices show promise in this context because they retain their magnetic state even when the power supply is switched off, something that it is not true for silicon memory chips. They also require much less power to operate and generate far less heat than their silicon counterparts.

One of the most important phenomena being studied in spintronics today is spin-orbit coupling, explains MIT Materials Research Laboratory co-director Geoffrey Beach, who led this research effort. “In many spintronics systems, emergent effects are generated at the interface between, for example, a metallic ferromagnet and a nonmagnetic heavy metal (like platinum or palladium),” he says. “Heavy metal/ferromagnetic interfaces have long been exploited to engineer magnetic thin films with perpendicular magnetic anisotropy, that is, films that spontaneously magnetize in a direction perpendicular to the film plane, which is required for most applications.”

Controlling magnetism using a proton pump, Belle Dumé, Physics World