High-profile Spin+X publication: Room-temperature spin-orbit torque in NiMnSb

Current research in spintronics focuses on the manipulation of magnetic moments by electrical means in a variety of spintronic structures. Here, spin-orbit coupling plays a key role and leads to a diversity of non-equilibrium spin-polarization phenomena, if inversion asymmetries are present in the investigated crystalline materials. Up to now, mainly magnetic transition-metal multilayers have been investigated to explore these relativistic spin-orbit torques, and the only so far known bulk-non-centrosymmetric ferromagnet material exhibiting these phenomena is the low-temperature diluted magnetic semiconductor (Ga,Mn)As.

An international research team from Cambridge , Würzburg, Mainz, Prague, Jülich and Nottingham that included two researchers from Spin+X, now published a new study in the area in the prestigious journal Nature Physics:
C. Ciccarelli, L. Anderson, V. Tshitoyan, A. J. Ferguson, F. Gerhard, C. Gould, L.W. Molenkamp, J. Gayles, J. Železný, L. Šmejkal, Z. Yuan, J. Sinova, F. Freimuth and T. Jungwirth:
Room-temperature spin–orbit torque in NiMnSb
Nature Physics, AOP 16 MAY 2016 | DOI: 10.1038/NPHYS3772

The researchers showed that the magnetic Heusler compound NiMnSb is another potential candidate for the presence of spin-orbit torques in non-centrosymmetric crystals, even at room-temperature. This specific compound was chosen out of there general framework of non-centrosymmetric crystals with potential presence of spin-orbit torques. Using the all-electrical ferromagnetic resonance technique they were able to detect room-temperature spin-orbit torques induced by the inverse spin galvanic effect with magnitudes that are consistent with their ab initio transport theory calculations. With their results, the team was able to prove the existence of spin-orbit torques in bulk-centrosymmetric crystals at room-temperature which are of high interest in terms of their potential utilization in spintronics devices.

Jairo Sinova and Jacob Gayles from Spin+X project A03 contributed important results regarding the theoretical modeling of the spin-orbit torques from a microscopic starting point. Their predictions are in full agreement with the observed experimental findings.