(a) A schematic of a Ho based spin spiral device. (b) Temperature dependence of the magnetic Bragg peak from a 50 nm Ho epitaxial film. View full-size image
Spintronics, technologies based on the use of the electron spin as opposed to conventional charge-based electronics, has seen enormous recent development.
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, email@example.com
Further reading: O Wessely et al., Phys Rev B 79 (2009) 104433