Direct observation of twisted surface Skyrmions in bulk crystals

Journal article

Magnetic skyrmions in noncentrosymmetric helimagnets with Dn symmetry are Bloch-type magnetization swirls with a helicity angle of ±90∘. At the surface of helimagnetic thin films below a critical thickness, a twisted skyrmion state with arbitrary helicity angle has been proposed, however, its direct experimental observation has remained elusive. Here, we show that circularly polarized resonant elastic x-ray scattering is able to unambiguously measure the helicity angle of surface skyrmions, providing direct experimental evidence that a twisted skyrmion surface state also exists in bulk systems. The exact surface helicity angles of twisted skyrmions for both left- and right-handed chiral bulk Cu2OSeO3, in the single as well as in the multidomain skyrmion lattice state, are determined, revealing their detailed internal structure. Our findings suggest that a skyrmion surface reconstruction is a universal phenomenon, stemming from the breaking of translational symmetry at the interface.

Authors: Zhang, S; van der Laan, G; Wang, W; Haghighirad, A; Hesjedal, T

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Letters
• Volume: 120
• Issue: 22
• Article number: 227202
• Publication date: 2018-05-31
• Acceptance date: 2018-04-13
• DOI: 10.1103/PhysRevLett.120.227202
• ISSN: 1079-7114 and 0031-9007