Saves Energy: Save Data with Topological Magnets

topological magnets
An electric field along the white arrow parallel to the magnetic insulator (orange), which is located on a substrate (gray), can control the orientation of the magnet (blue arrow). If the topological properties change from A to B, the energy bands (green and red) must intersect in the case of a magnetic insulator. The physicists showed that such crossing points (gray sphere) can be used for a particularly efficient switching of the magnet. Copyright: Forschungszentrum Jülich

Saving, reading and writing information quickly, energy-savingly and in the tightest of spaces is a fundamental requirement for today’s and future information stores. Magnetic materials, such as those used in billions of hard disks, are particularly well-tried carriers of information.Physicists at Forschungszentrum Jülich have now shown that the control of the magnetic orientation in certain insulators using electric fields should be even better. The scientists were also able to use computer simulations to suggest promising materials in which this phenomenon could be experimentally demonstrated.

As a result of the so-called spin-orbit interaction, an electric field can exert a force on a magnet, causing it to change its magnetic orientation in space. While so far predominantly metallic solids have been investigated in this context, the Jülich researchers instead focused on insulating systems. In contrast to metals, the electrical conductivity and corresponding energy losses in these materials are negligible.

The researchers discovered that virtually loss-free switching of the magnet is possible precisely when, due to a phase transition, the topology of the insulator changes with its magnetic orientation. Topology is a mathematical concept and describes that basic properties of objects under continuous deformation remain the same. For example, it is not possible to reshape the letter B into the letter A only by stretching and bending it. In their publication in the journal Nature Communications, the physicists continue to report how their findings can help to develop new insulating and metallic magnets for the data storage of the future.

original publication

Jan-Philipp Hanke, Frank Freimuth, Chengwang Niu, Stefan Blügel, Yuriy Mokrousov; Mixed Weyl semimetals and low-dissipation magnetization control in insulators by spin-orbit torques; Nature Communications 8, 1479 (2017),

Source : Forschungszentrum Jülich