Theory of chiral modulations in confining structures: epitaxial films of cubic helimagnets
Final Report Abstract
The project is dedicated to the development of a comprehensive theory of chiral modulations in nanolayers of magnetic materials with the intrinsic (cubic helimagnets) and induced (bilayers of FePd/Ir (111)) DM interactions. The theoretical investigations have been carried out in a close collaboration with several experimental group. The main findings of the project include the following results. (i) We have demonstrated that the surface chiral twists discovered in our previous papers provide a stabilization mechanism for magnetic skyrmions in confined noncentrosymmetric ferromagnets and developed a theory of magnetization processes in nanolayers of cubic helimagnets. Detailed LTEM investigations in FeGe wedges at Osaka and Glasgow universities have supported our theoretical findings. (ii) We have developed a comprehensive theory of isolated skyrmions in magnetic nanolayers and in collaboration with R. Wiesendanger group (Humburg university) have carried out detailed investigations of an isolated skyrmion evolution in FePd/Ir (111) bilayers. (iii) We apply our theory of skyrmionic states in confined noncentrosymmetric systems to describe skyrmionic states recented discovered in chiral liquid crystal layers with homeotropic anchoring (I. Smalyukh group, Colorado university, USA). (iv) The theoretical prediction, mathematical analysis, and direct observations of new class of magnetic skyrmions is an unexpected (“surprising”) contribution into the project. These three-dimensional nonaxisymmetric solitonic states arise in the cone phases of noncentrosymmetric ferromagnets and are fundamentally different from the known axisymmetric skyrmions dwelling in the saturated states. Our joint work with J. Loudon group (Cambridge, UK) has resulted in the discovery of the attractive skyrmions and their clusters in nanolayers of cubic helimagnets Cu2OSeO3.
Publications
- Surface twists instabilities and skyrmion states in chiral ferromagnets, Phys. Rev. B 90 , 014406 (2014)
S. A. Meynell, M. N. Wilson, H. Fritzsche, A. N. Bogdanov, T. L. Monchesky
(See online at https://doi.org/10.1103/PhysRevB.90.014406) - Chiral Surface Twists and Skyrmion Stability in Nanolayers of Cubic Helimagnets, Phys. Rev. Lett. 117, 087202 (2016)
A. O. Leonov, Y. Togawa, T. L. Monchesky, A. N. Bogdanov, J. Kishine, Y. Kousaka, M. Miyagawa, T. Koyama, J. Akimitsu, Ts. Koyama, K. Harada, S. Mori, D. McGrouther, R. Lamb, M. Krajnak, S. McVitie, R. L. Stamps, K. Inoue
(See online at https://doi.org/10.1103/PhysRevLett.117.087202) - Internal structure of hexagonal skyrmion lattices in cubic helimagnets. New J. Phys. 18, 095004 (2016)
D. McGrouther, R. J. Lamb, M. Krajnak, S. McFadzean, S. McVitie, R. L. Stamps, A O Leonov, A N Bogdanov, and Y Togawa
(See online at https://doi.org/10.1088/1367-2630/18/9/095004) - The properties of isolated chiral skyrmions in thin magnetic films. New J. Phys. 18, 065003 (2016)
A. O. Leonov, T. L. Monchesky, N. Romming, A. Kubetzka, A.N. Bogdanov, R. Wiesendanger
(See online at https://doi.org/10.1088/1367-2630/18/6/065003)
