Stability of Skyrmions and Topological Hall Effect in Mn₂CoAl thin films

Skyrmions are magnetic quasi-particles that have the potential to help resurrect Moore’s Law.^[1] Due to their topological protection, they could be used as non- volatile memory,^[2] while also allowing the design of logic gates^[3] that could be used in magnonic devices.
The presence of skyrmions can be detected by observing the topological contribution to the Hall resistance, due to the time-varying magnetic field experienced by an electron travelling through a material hosting skyrmions. We observe skyrmions in thin films of the ferromagnetic spin-gapless semiconductor Heusler alloy Mn₂CoAl capped by Pd.^[4] We can engineer our thin films to make the skyrmions stable from 3K to above room temperature. By careful control of the magnetic and thermal history of the sample, we can condition various forms of skyrmions in this material. In order to understand their stability, we have measured time dependent Hall resistance and magnetization in the skyrmion regions. We observe skyrmions that are stable for at least hours at room temperature in the absence of a magnetic field.

References:
1 D. Chandler, MIT News., 2017
2 A. Fert, V. Cros, and J. Sampaio, Nat. Nanotechnol., 2013, 8, 152–156 (2013).
3 S. Luo et al., Nano Lett., 2018, 18, 1180-1184
4 B. Ludbrook et al., Sci. Rep., 2017, 13620