Room Temperature Magnetic Skyrmions in Engineered Multilayer Films

Who: Geoffrey Beach, Massachusetts Institute of Technology
When: 
Friday, April 14, 2017 - 11:30am to 12:30pm
Where: 
Doherty Hall 2315

Magnetic skyrmions [1] are particle-like twists of the magnetization taking the form of nanoscale vortices or bubbles that are topologically protected from being continuously ‘unwound’. Their small size, high stability, and ease of manipulation by electric current make them strong candidates for use as information carriers in spintronic memory and logic devices. However, magnetic skyrmions have until recently been restricted to just a few materials and observed only at low temperatures, limiting the experimental accessibility and technological application of these unique topological objects. This talk focuses on magnetic skyrmions in ultrathin ferromagnetic transition metal multilayers in which interfaces with heavy metals generate a strong Dzyaloshinskii-Moriya interaction (DMI) that can stabilize chiral magnetic order [2,3]. By tuning the relevant magnetic energy terms in inversion-asymmetric engineered multilayer stacks, we show that magnetic skyrmions can be stabilized at room temperature using materials that are amenable to integration with CMOS. Using high-resolution x-ray microscopy, we reveal the current-driven dynamics of skyrmions in racetracks, demonstrate that skyrmions can be generated deterministically by nanosecond current pulses, and present an analytical framework to compute the properties of any skyrmion in any material, allowing large-scale multi-parameter-space studies of skyrmion properties and revealing new and unexpected behaviors.

[1] U. Rößler, A. N. Bogdanov, C. Pfleiderer, C., Nature 442, 797-801 (2006)
[2] S. Emori, et al., Nat. Mater. 12, 611–616 (2013)
[3] S. Woo, et al., Nature Mater. 15, 501 (2016)
[4] K. Litzius, et al., Nature Phys. 13, 170 (2017)