In the mid-nineties it was proposed that a spin-polarized current of electrons would be able to rotate its magnetisation, removing the need for applied magnetic fields. This has been demonstrated – however, the primary hurdle for making use of these devices is the prohibitively high switching current densities required. An alternative is to use a spin-spiral material, such as holmium. Holmium is ferromagnetic, but the moments rotate from one plane to the next in a spiral fashion. In devices, the entire spin-spiral can be employed in the switching, thereby lowering the necessary current densities. Using polarised neutron reflectometry we have been able to study the temperature and layer thickness dependence of the spin-spiral in films only 25 atomic layers thick. Such information is essential to produce optimised spin-spiral devices.
J Witt, A Aziz, M Blamire, (Cambridge University), R Fan, C Kinane, T Charlton, S Langridge (ISIS)
Contact: James Witt, firstname.lastname@example.org
Further reading: O Wessely et al., Phys Rev B 79 (2009) 104433