Kitaev anisotropy induces mesoscopic Z(2) vortex crystals in frustrated hexagonal antiferromagnets

Article

关键词: CONTINUOUS SYMMETRY GROUP;    REAL-SPACE OBSERVATION;    LONG-RANGE ORDER;    HEISENBERG-ANTIFERROMAGNET;    2-DIMENSIONAL SYSTEMS;    MAGNETIC MONOPOLES;    SKYRMION LATTICE;    PHASE-TRANSITION;    TEMPERATURE;    DESTRUCTION;   

DOI  :  10.1103/PhysRevB.93.104417

来源: SCIE

【 摘 要 】

The triangular-lattice Heisenberg antiferromagnet (HAF) is known to carry topological Z(2) vortex excitations which form a gas at finite temperatures. Here we show that the spin-orbit interaction, introduced via a Kitaev term in the exchange Hamiltonian, condenses these vortices into a triangular Z(2) vortex crystal at zero temperature. The cores of the Z(2) vortices show abrupt, soliton-like magnetization modulations and arise by a special intertwining of three honeycomb superstructures of ferromagnetic domains, one for each of the three sublattices of the 120 degrees state of the pure HAF. This is an example of a nucleation transition, analogous to the spontaneous formation of magnetic domains, Abrikosov vortices in type-II superconductors, blue phases in cholesteric liquid crystals, and skyrmions in chiral helimagnets. As the mechanism relies on the interplay of geometric frustration and spin-orbital anisotropies, such vortex mesophases can materialize as a ground state property in spin-orbit coupled correlated systems with nearly hexagonal topology, as in triangular or strongly frustrated honeycomb iridates.

【 授权许可】

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