Thin Films Give Magnets a Stronger Twist express
A magnet in a microchip is like a compass needle that needs to be turned without touching it. Usually, heavy metals are used for this, but they heat up and waste energy. Physicists have found a replacement — a layered material called GeTe, which resembles a stack of ultra-thin sheets.
In the experiment, current was passed through the interface between the magnetic alloy NiFe and GeTe. The electric flow caused the magnetization to rotate with a strength that was previously thought impossible for such layered materials. The value even exceeded that of the best heavy metals: −(1.25 ± 0.11) × $10^5$ (ħ/2e) Ω⁻¹·m⁻¹.
The secret lies in the combined action of three effects. The electron's spin (its tiny magnetic moment) and its orbital motion work together, and the interface between materials helps transmit the torque. Computer calculations confirmed that charge flows across the junction and enhances the rotation.
Now engineers can build memory and logic microchips that consume less energy for switching. Thin films of GeTe pave the way for devices where a magnet is controlled by current with almost no loss — all at room temperature.
Original abstract
as written by the authors arXiv:2601.12581
Recent observations of large unconventional spin-orbit torques in van der Waals (vdW) materials are driving intense interest for energy-efficient spintronic applications. A key limitation of ferromagnet (FM)/vdW heterostructures is their lower value of damping-like torque conductivity ($$\sigma{\rm_{DL}^{y}}$$) compared to the conventional heavy metal-based systems, limiting their prospects for commercial spintronic devices. Here, we report both a giant $$\sigma{\rm_{DL}^{y}}$$ of $$-(1.25 \pm 0.11)\times 10^{5}~\hbar/ 2e~\Omega^{-1}$$m$$^{-1}$$ and an unconventional spin-orbit torque in a heterostructure comprising an FM (Ni$$_{80}$$Fe$$_{20}$$) and the vdW material GeTe. The value of $$\sigma{\rm_{DL}^{y}}$$ represents the highest reported torque conductivity for any FM/vdW interface and is comparable to benchmark heavy metal heterostructures. First-principles calculations reveal that this substantial torque originates from the cooperative interplay of the spin Hall effect, orbital Hall effect, and orbital Rashba effect, assisted by interfacial charge transfer. These findings demonstrate the potential of carefully engineered vdW heterostructures to achieve highly efficient electrical manipulation of magnetization at room temperature, paving the way for next-generation low-power spintronic devices.
Germanium telluride is the same material used in rewritable DVDs: when heated, it changes its structure, and a laser reads the difference.