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Séminaire Magnétisme non conventionnel

Jeudi 22 Mars à 14h00
Salle Remy Lemaire K223

Orateur : Karim ESSAFI (LPTMC, Paris)
"Generic Nearest-Neighbour Hamiltonian on Kagome"


Competing interactions in frustrated magnets prevent ordering down to very low temperatures and stabilize exotic highly degenerate phases where strong correlations coexist with fluctuations. We study the fully anisotropic nearest-neighbour model on kagome, whose ground state is described by a variety of exotic (chiral) phases, including classical spin liquids. The Hamiltonian can be locally defined as an XYZ model with out-of-plane Dzyaloshinskii-Moriya interactions. We proceed to study its phase diagram in the classical limit, making use of an exact reformulation of the Hamiltonian in terms of irreducible representations (irreps) of the lattice symmetry group. Several unusual states are stabilized in the regions where different forms of ground-state order compete, including a stripy phase with a local Z8 symmetry and a classical analog of a chiral spin liquid. As a peculiar property of the kagome lattice, the generic model turns out to be a fruitful hunting ground for the coexistence, in the same ground-state configuration, of multiple forms of long-range magnetic orders. In addition, when coupled with itinerant electrons, the chiral phases display a finite Hall conductivity.

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