Formation Of Spin Textures Research Articles

Evolution of the Spin Order in Hall Ferromagnets under the Strong Mixing of Landau Levels and at the Filling Factors 1 ≤ ν ≤ 2

An unconventional behavior of the spin order in strongly correlated two-dimensional electron systems based on MgZnO/ZnO heterostructures has been detected in the quantum limit at the filling factors 1 ≤ ν ≤ 2. Under the variation of the filling factor and the orientation of a magnetic field, inelastic light scattering spectra exhibit characteristic transformations of collective spin excitations, which indicate qualitatively different rearrangements of the spin configuration in the system: smooth depolarization at 1 < ν < 3/2 with the formation of spin textures and sharp ferromagnetic instability at a certain filling factor in the range 3/2 < ν ≤ 2. Comparison with the magnetotransport experiments reported in [J. Falson, D. Maryenko, B. Friess, et al., Nature Phys. 11, 347 (2015)] shows that the disappearance of spin textures under the variation of the field tilt angle correlates with the appearance of an incompressible state at ν = 3/2.

Evidence of the Topological Hall Effect in Pt/Antiferromagnetic Insulator Bilayers.

The topological Hall effect has been a primary indicator of nontrivial spin textures in magnetic materials. We observe the evidence of the topological Hall effect in Pt/Cr_{2}O_{3} bilayers grown on Al_{2}O_{3}(0001) and Al_{2}O_{3}(112[over ¯]0), where the Cr_{2}O_{3} epitaxial film is an antiferromagnetic insulator. The Pt/Cr_{2}O_{3} bilayers exhibit topological Hall resistivity for Cr_{2}O_{3} thicknesses below 6nm near and above room temperature, which is above the Néel temperature of Cr_{2}O_{3}, revealing the key role of thermal fluctuations in the formation of spin textures. The similarity of topological Hall signals in (0001)- and (112[over ¯]0)-oriented Cr_{2}O_{3} films indicates that the emergence of spin textures is insensitive to crystalline orientation.

Ground states, solitons and spin textures in spin-1 Bose-Einstein condensates

We present an overview of our recent theoretical studies on the quantum phenomena of the spin-1 Bose-Einstein condensates, including the phase diagram, soliton solutions and the formation of the topological spin textures. A brief exploration of the effects of spin-orbit coupling on the ground-state properties is given. We put forward proposals by using the transmission spectra of an optical cavity to probe the quantum ground states: the ferromagnetic and polar phases. Quasi-one-dimension solitons and ring dark solitons are studied. It is predicted that characteristics of the magnetic solitons in optical lattice can be tuned by controlling the long-range light-induced and static magnetic dipoledipole interactions; solutions of single-component magnetic and single-, two-, three-components polar solitons are found; ring dark solitons in spin-1 condensates are predicted to live longer lifetimes than that in their scalar counterparts. In the formation of spin textures, we have considered the theoretical model of a rapidly quenched and fast rotating trapped spin-1 Bose-Einstein condensate, whose dynamics can be studied by solving the stochastic projected Gross-Pitaevskii equations. Spontaneous generation of nontrivial topological defects, such as the hexagonal lattice skyrmions and square lattice of half-quantized vortices was predicted. In particular, crystallization of merons (half skyrmions) can be generated in the presence of spin-orbit coupling.