TY - JOUR
T1 - Kitaev anisotropy induces mesoscopic Z2 vortex crystals in frustrated hexagonal antiferromagnets
AU - Rousochatzakis, Ioannis
AU - Rössler, Ulrich K.
AU - Van Den Brink, Jeroen
AU - Daghofer, Maria
N1 - Publisher Copyright:
© 2016 American Physical Society.
PY - 2016/3/17
Y1 - 2016/3/17
N2 - The triangular-lattice Heisenberg antiferromagnet (HAF) is known to carry topological Z2 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 Z2 vortex crystal at zero temperature. The cores of the Z2 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 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.
AB - The triangular-lattice Heisenberg antiferromagnet (HAF) is known to carry topological Z2 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 Z2 vortex crystal at zero temperature. The cores of the Z2 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 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.
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U2 - 10.1103/PhysRevB.93.104417
DO - 10.1103/PhysRevB.93.104417
M3 - Article
AN - SCOPUS:84962023232
SN - 2469-9950
VL - 93
JO - Physical Review B
JF - Physical Review B
IS - 10
M1 - 104417
ER -