Séminaire exceptionnel du LPTMS : Daniel Cabra


14:30 - 15:30

LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay
15 Rue Georges Clemenceau, Orsay, 91405

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Skyrmion Lattices in Antiferromagnetic Systems

Daniel C. Cabra  (University of La Plata)

Ordering of the frustrated classical Heisenberg model with Dzyaloshinskii-Moriya (DM) interactions on the antiferromagnetic triangular lattice is studied under a magnetic field by means of semiclassical calculations and large-scale Monte Carlo simulations. We show that even a small DM interaction induces the formation of anAntiferromagneticSkyrmion crystal (AF-SkX) state. Unlike what is observed in ferromagnetic materials, we show that the AF-SkX state consists of three interpenetrating usual Skyrmion crystals (one by sublattice), and most importantly, the AF-SkX state survives in the limit of zero temperature. To characterize the phase diagram we compute the average of the topological order parameter, the chirality, which measures the numberof Skyrmions. As themagneticfieldincreases, this parameter presents a series of discrete jumps that may indicate transitions between different topological states. Increasing the magnetic field the model exhibits a first-order transition from a spiral phase into a three-sublattice Skyrmion structure where multiple Bragg peaks coexist in the spin structure factor.

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