5 µm

1. Materials World Network: Magnetic Properties of Mesoscopic Multilayer RingsCaroline A. Ross, Massachusetts Institute of Technology, DMR 0709557 In this project, we are exploring magnetic multilayer rings which can be used as nonvolatile memory or logic devices. We showed that rings could interact magnetostatically, allowing one to control the switching of another. This enables devices in which information propagates between devices via magnetostatic interactions, or a spin polarized current. We investigated 360 degree domain walls: their formation, current-induced reversal, and dynamic behavior. They could serve as a possible new data storage token, or as GHz oscillators. We also looked at rhombic GMR ring devices including their switching mechanism, statistics and reproducibility. Micromagnetic model of a 360 degree wall, and an image of one in a Co ring. 5 µm 200 nm Pairs of interacting rings with electrical contacts, allowing their influence on each other to be probed using magnetoresistance.

2. Materials World Network: Magnetic Properties of Mesoscopic Multilayer Rings Caroline A. Ross, Massachusetts Institute of Technology, DMR 0709557 This is a collaborative project between researchers in MIT and in Cambridge University, UK. The broader impacts of the work include training and joint educational activities as well as lectures to a teachers’ group. Elle Lee, the UK student, is close to graduating. We have interacted with her frequently, including visits, provided samples for measurements, and served as a mentor. We also hosted a visiting German student, Helmut Korner, who worked on rhombic rings and on the properties of arrays of magnetic dots. Results from Cambridge collaboration: split rings for spin-FET electrodes Magnetic states in rhombic rings made of Co, 2 µm long