Role of Atomic Hydrogen in Tailoring Noncollinear Magnetic Spin Textures

Pin-Jui Hsu^1*

¹Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Pin-Jui Hsu, email:pinjuihsu@phys.nthu.edu.tw

Abstract:
A new class of noncollinear magnetic spin structures, i.e., chiral domain walls, cycloidal spin spirals and Néel-type skyrmions, have been recently discovered in ultrathin transition metal films grown on heavy-element substrates [1-3]. Due to a lack of structural inversion symmetry at interfaces, they exhibit a unique rotational sense as a consequence of interfacial Dzyaloshinskii-Moriya (DM) interactions [4]. In this talk, I will report on the vital role of atomic hydrogen in tailoring such chiral spin textures. While a nanoskyrmion lattice was revealed for Fe monolayers (ML) grown on Ir(111) [5], a cycloidal spin spiral ground state has been resolved on Fe double-layers (DL) by employing SP-STM with vector magnetic fields [6]. The magnetic phase transition is absent at both pristine Fe-ML and DL systems up to 9 tesla (T) of out-of-plane magnetic field. After dosing hydrogen atoms onto the Fe-ML, the hexagonal nanoskyrmion lattice appears and exhibits a domain reversal behavior when external magnetic fields are applied. As for the hydrogenated Fe-DL, we have observed the magnetic skyrmions and ferromagnetism at different structural phases, which can be associated with adsorbed hydrogen atoms in tuning Heisenberg exchange and DM interactions at the atomic level [7]. Hydrogenation thus provides a unique pathway to engineer crucial magnetic parameters leading to a drastic change on noncollinear magnetism in low-dimensional magnetic materials.

References:
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6. Hsu, P.-J. et al. Guiding spin spirals by local uniaxial strain relief. Phys. Rev. Lett. 116, 017201 (2016).
7. Hsu, P.-J. et al. Inducing skyrmions in ultrathin Fe films by hydrogen exposure. Nat. Commun. 9, 1571 (2018).

Keywords: Magnetic Skyrmions, Iron Films, Spin-Orbit Coupling, Atomic Hydrogen, Spin-Polarized STM