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Séminaire Magnétisme non conventionnel

Jeudi 19 décembre 2019 à 14h00,
Salle Remy Lemaire, K223

Orateur : Tristan LUGAN (Institut Néel)
"Topological Nematic Spin Liquid on the Square-Kagome Lattice"


In this presentation, I will present the study of the phase diagram of a spin-1/2 J1-J2 Heisenberg model on the frustrated square-kagome geometry [1]. The asymptotic limits are reasonably well understood (J1 << J2 & J2 >> J1), but as usual in frustrated magnetism, the most promising, intermediate, regime remains elusive. Here we show that this regime supports exotic magnetic phases within Schwinger boson mean field theory, a bosonic parton construction. In particular, I will describe a new gapped topological quantum spin liquid with a weak lattice nematicity characterized by specific gauge invariant quantities. The associated fourfold topological degeneracy will be evidenced by help of non-local winding fluxes. I will also report the existence of two close yet different incommensurate orders from which our topological nematic spin liquid (TNSL) arises by quantum melting. In order to make contact with the recent synthesis of similar square- kagome spin- 1/2 compound [2], I will finally discuss the potential experimental signatures of the different phases, such as their dynamical structure factors.
[1] T. Lugan, L.D.C Jaubert, A. Ralko, arXiv (2019), 1907.02883, to be published in Physical Review Research.
[2] K. Morita and T. Tohyama, Journal of the Physical Society of Japan 87, 043704 (2018).

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