Prediction and discovery of all-quantum skyrmions at room temperature

Room temperature skyrmions were recently observed in ferromagnetic multilayers [1–4]. Surprisingly, they were all at least several tens of nanometer in diameter. Their large size has a fundamental origin: these skyrmions are stabilized by a competition of classical long range fields, namely stray fields and externally applied fields. Based on accurate analytical modeling, we could show that this is a general property of ferromagnets due to their overwhelming stray fields [5].
In ferri- and antiferromagnetic materials, stray fields play no significant role. We predicted theoretically [5] and confirmed experimentally [6] that a different type of skyrmion can exist in these materials at room temperature, stabilized by all-quantum interactions. These skyrmions are insensitive to classical fields, exist even at zero external field, and can be as small as ~10 nm in diameter. Finally, they are also created by quantum spin-orbit torques [7].

[1] Büttner et al. Nat Phys 11, 225 (2015)
[2] Woo et al. Nat Mat 15, 501 (2016)
[3] Moreau-Luchaire et al. Nat Nano 11, 444 (2016)
[4] Boulle et al. Nat Nano 11, 449 (2016)
[5] Büttner et al. Sci Rep 8, 4464 (2018)
[6] Caretta, Mann, Büttner, et al. Nat Nano in press (2018). doi:10.1038/s41565-018-0255-3
[7] Büttner et al. Nat Nano 12, 1040 (2017)