Print Email Facebook Twitter Skyrmion clusters and conical droplets in bulk helimagnets with cubic anisotropy Title Skyrmion clusters and conical droplets in bulk helimagnets with cubic anisotropy Author Leonov, A.O. (Hiroshima University; IFW Dresden) Pappas, C. (TU Delft RST/Neutron and Positron Methods in Materials) Date 2019 Abstract Recent experimental findings in the bulk cubic helimagnet and Mott insulator Cu2OSeO3 highlight the paramount role of cubic anisotropy in stabilizing novel chiral and skyrmion phases. It was indeed found that if a magnetic field is applied along the easy 001 crystallographic direction, competing cubic andexchange anisotropies tilt the wave vector of the conical spiral away from the magnetic field [Qian et al., Sci. Adv. 4, eaat7323 (2018)]. Furthermore, in this configuration skyrmions have been observed in a broad range of temperatures and magnetic fields [Chacon et al., Nat. Phys. 14, 936 (2018)]. Starting from theseexperimental observations and on the basis of a phenomenological Dzyaloshinskii theory, we investigate additional implications of the cubic anisotropy for this specified field direction. By including cubic anisotropy we show that the phase transition between the conical and field-polarized or homogeneous states becomes first order. Furthermore, we show that this transition is accompanied by the formation of conical droplets—domains of the conical phase in the homogeneous state. We investigate the internal structure of these droplets, which at their boundaries encompass alternating regions of positive and negative energy densities with respect tothe homogeneous state. We thus deduce that these droplets may be zipped and unzipped in phase during the first-order phase transition that occurs by either increasing or decreasing the magnetic field. On the other hand, we show that in the conical phase skyrmions may form clusters due to their attractive mutual interaction. However, inthe homogeneous state, the skyrmion-skyrmion interaction becomes repulsive, and the skyrmion clusters expand and disperse isolated skyrmions. This mutual skyrmion repulsion prevents the stabilization of skyrmion clusters even if the energy of isolated skyrmions is lower than that of the homogeneous state. Yet this skyrmion dispersalmay be prevented if skyrmions are surrounded by the circular spiral state and form skyrmion bags. Such a scenario could explain the existence of skyrmions in the field-polarized state reported experimentally. To reference this document use: http://resolver.tudelft.nl/uuid:7b566c2e-e3df-4387-aa7a-10163dcb9169 DOI https://doi.org/10.1103/PhysRevB.99.144410 ISSN 2469-9950 Source Physical Review B, 99 (14) Part of collection Institutional Repository Document type journal article Rights © 2019 A.O. Leonov, C. Pappas Files PDF PhysRevB.99.144410.pdf 4.24 MB Close viewer /islandora/object/uuid:7b566c2e-e3df-4387-aa7a-10163dcb9169/datastream/OBJ/view