a room-temperature magnetoelectric memory device, engineers at Cornell
University have made a breakthrough that may lead to instant-start computers. To encode data, today’s computer memory
technology uses electric currents – a major limiting factor for reliability and
shrinkability, and the source of significant power consumption. If data could
instead be encoded without current – for example, by an electric field applied
across an insulator – it would require much less energy, and make things like
low-power, instant-on computing a ubiquitous reality.
team at Cornell University led by postdoctoral associate John Heron, who works
jointly with Darrell Schlom, professor of Industrial Chemistry in the
Department of Materials Science and Engineering, and Dan Ralph, professor of
Physics in the College of Arts and Sciences, has made a breakthrough in that
direction with a room-temperature magnetoelectric memory device. Equivalent to
one computer bit, it exhibits the holy grail of next-generation nonvolatile
memory: magnetic switchability, in two steps, with nothing but an electric
field. Their results were published online December 17 in Nature, along with an
associated “News and Views” article.
advantage here is low energy consumption,” Heron said. “It requires a low
voltage, without current, to switch it. Devices that use currents consume more
energy and dissipate a significant amount of that energy in the form of heat.
That is what’s heating up your computer and draining your batteries.” The
researchers made their device out of a compound called bismuth ferrite, a
favorite among materials mavens for a spectacularly rare trait: It’s both
magnetic – like a fridge magnet, it has its own, permanent local magnetic field
– and also ferroelectric, meaning it’s always electrically polarized, and that
polarization can be switched by applying an electric field. Such so-called
ferroic materials are typically one or the other, rarely both, as the
mechanisms that drive the two phenomena usually fight each other.
paper, “Deterministic Switching of Ferromagnetism at Room Temperature Using an
Electric Field,” includes collaborators from University of Connecticut; University
of California, Berkeley; Tsinghua University; and Swiss Federal Institute of
Technology in Zurich. The research was supported by the National Science
Foundation and the Kavli Institute at Cornell for Nanoscale Science, of which
Ralph and Schlom are both members.
Vasyl Kacapyr, Cornell University