Researchers uncover "unexpected effect" that could help create low-power memory modules

New process could lead to much lower-power memory and computing devices

Scientists have stumbled across an unexpected electro-magnetisation effect that, they claim, could lead to much lower-power memory modules and, hence, computing devices.

The scientists made the claimed discovery while studying the electrical properties of combinations of metals layered on a silicon substrate together with a thin cobalt-iron-boron (CoFeB) magnetic layer.

The nanometer-thick CoFeB magnet is able to store a bit of data by virtue of the direction of its magnetisation: up (1) or down (0).

The research project, led by John Hopkins University and the US National Institute of Standards and Technology (NIST), found that this magnetisation could be changed simply by passing a current through the metal (platinum and tungsten) layers. Previous experiments had also required the application of a magnetic field for the switch to be observed.

The scientists said the discovery was "surprise" and that the effect "had not been theoretically predicted".

If it scales up this Zero Field Switching (ZFS) effect could allow for a new generation of stable non-volatile, low energy memory devices.

During the study, the researchers generated a spin current, produced when the spins of the electrons are pointing in the same direction. When the spin current flowed adjacent to the CoFeB magnetic layer it was observed to exert a torque on that layer, causing its magnetisation to be flipped. In the absence of the spin current the CoFeB magnetisation was stable over a range of temperatures and fluctuations in the current.

The researcher say the unexpected ZFS effect "poses new questions to theorists about the underlying mechanism of the observed SOT [spin-orbit torque]-induced switching phenomenon".

The academics are now working to "identify other prospective materials that enable zero-field-switching of a single perpendicular nanomagnet".

Future experiments will also explore "ZFS behaviour changes for nanomagnets possessing smaller lateral sizes and developing the theoretical foundation for this unexpected switching phenomenon", explained the researchers.

The research team consisted of NIST scientists Daniel Gopman, Robert Shull and Yury Kabanov, along with Johns Hopkins University researchers Qinli Ma, Yufan Li and Professor Chia-Ling Chie.