Beyond Dzyaloshinskii-Moriya: anisotropy-driven compact spin textures for low-power spintronics

Demand for denser, lower-power data storage keeps rising, yet the metallic magnets behind most memory technologies dissipate energy through electrical currents. Magneto-electric insulators on the other hand offer an alternative: carrying no itinerant current, they allow magnetic information to be written with an electric field rather than a current, lowering power consumption by orders of magnitude while avoiding resistive heating. Using them for dense storage requires the magnetic textures themselves to be small, a few nanometres across, so that many bits fit in a given area. The usual ingredient for forming such textures, the Dzyaloshinskii-Moriya interaction (DMI), typically fixes their period at tens of nanometres, too large for high-density integration. Finding insulating hosts in which a different mechanism compresses these textures is therefore a central goal.

 Writing in Research, a team from PSI and EPFL has identified the chiral cubic oxide Co₅TeO₈ as a strongly correlated insulator that meets these requirements. Combining neutron scattering, magnetometry, and capacitance measurements, the team mapped a phase diagram containing eight distinct magnetic phases and found capacitance anomalies across it, a signature of magneto-electric coupling that points to possible electric-field control. Small-angle neutron scattering (at SANS-I, SINQ) with polarisation analysis (at D33, ILL) showed that the magnetic order is a Bloch-type helical spiral with a tunable pitch length between 5.7 and 10 nm, among the shortest reported for any chiral insulator. To identify what sets this short period, the team carried out ab initio quantum-chemistry calculations, which place the single-ion anisotropy (SIA) at least an order of magnitude above both the DMI and the exchange interactions. The results point to a stabilisation mechanism distinct from conventional helimagnets: frustration opens a near-degenerate manifold of spiral states and DMI fixes their handedness, while the dominant site-dependent SIA selects the period. Co₅TeO₈ thus offers a design principle for engineering compact spin textures and a candidate platform for low-power magneto-electric spintronics.