MATERIALS SCIENCE COLLOQUIUM

Refreshments will be served at 10:45 a.m.

ABSTRACT: In most magnetic applications the orientations of the magnetic elements are controlled by external magnetic fields. However, it has recently been appreciated that the relative orientations of nano-magnets can be controlled directly by the injection of spin polarized currents known as spin transfer effects. The ability of a spin-polarized current to reverse the magnetization orientation of a nanomagnets should enable a range of devices such as high performance random-access magnetic memories and spin-oscillators [1]. In this presentation I will review the basic properties of spin-transfer and highlight recent research on spin-transfer effects in nano-elements having strong perpendicular magnetic anisotropy [2,3]. This perpendicular geometry has a number of advantages including efficient coupling of the spin-current to magnetic excitations, narrow (<10 nm) domain walls that interact more strongly with the electron spin, and higher magnetic resonance frequencies. I’ll describe recent experimental and theoretical studies of the influence of spin currents on the field and angular dependence of the free layer switching fields, scaling of critical currents with energy barrier heights and the efficiency of spin currents on domain wall depinning.
[1]. J. A. Katine and E. E. Fullerton, J. Magn. Magn. Mater. 320, 1217 (2008).
[2] S. Mangin et al., Nature Mater. 5, 210 (2006).
[3] C. Burrowes et al., Nature Physics 6, 17 (2009).