Chemisorption-Induced Dzyaloshinskii-Moriya Interactions*

Chiral spin textures lead to a host of fascinating phenomena due to their topologically protected spin configurations and emergent electromagnetic field, offering great potential for novel concepts in low dissipation magnetic information storage [1-3]. The most widely used mechanism to stabilize magnetic chirality is the Dzyaloshinskii–Moriya interaction (DMI), originating from broken inversion symmetry. To date, sufficiently large DMI has been found in a limited set of bulk materials with chiral lattice, and in magnetic thin films adjacent to heavy metals or oxides.

Using a magnetic imaging technique, we have previously discovered that chiral spin textures are induced at graphene/ferromagnet interfaces due to a Rashba-type DMI [4]. More recently, we have found that chemisorbed species such as oxygen [5] (which is different from the ionic oxygen in oxides) and hydrogen [6] on the surface of ferromagnetic films can induce significant DMI, despite their low atomic number. We find that the DMI at the oxygen/ferromagnet interface is comparable to that at ferromagnet/transition-metal interfaces. This large DMI has enabled direct tailoring of skyrmions winding number and wall type at room temperature via oxygen chemisorption. We have also demonstrated a sensitive and reversible chirality switching of magnetic domain walls via hydrogen chemisorption/desorption [6]. These results extend the understanding of the DMI induced by the light elements and support chemisorption related design of spin-orbitronics and magneto-ionic devices.

[1] R. Wiesendanger, Nat. Rev. Mater. 1, 16044 (2016).
[2] A. Fert, et al. Nat. Rev. Mater. 2, 17031 (2017).
[3] W. Jiang, et al. Phys. Rep. 704, 1 (2017).
[4] H. Yang, G. Chen, et al. Nat. Mater. 17, 605 (2018).
[5] G. Chen, et al. Sci. Adv. 6, eaba4924 (2020).
[6] G. Chen, et al. under review.