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Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons: Spin Systems and Itinerant Magnets – Frustrated Magnets 1 (jointly with MA)

TT 5.12: Vortrag

Montag, 16. März 2015, 12:30–12:45, H 0110

The spin-1/2 Heisenberg J1J2 antiferromagnet on the kagome lattice — •Yasir Iqbal1, Didier Poilblanc2, and Federico Becca31Institute for Theoretical Physics and Astrophysics, Julius-Maximilian’s University of Würzburg, Am Hubland, D-97074, Würzburg, Germany — 2Laboratoire de Physique Théorique UMR-5152, CNRS and Université de Toulouse, F-31062 Toulouse, France — 3Democritos National Simulation Center, Istituto Officina dei Materiali del CNR and SISSA-International School for Advanced Studies, Via Bonomea 265, I-34136 Trieste, Italy

We report numerical calculations for the spin-1/2 Heisenberg model in presence of both nearest-neighbor J1 and next-nearest-neighbor J2 antiferromagnetic super-exchange couplings. Our approach is based upon Gutzwiller projected fermionic states that represents a flexible tool to describe quantum spin liquids with different properties (e.g., gapless and gapped). We show that, on finite clusters, a gapped Z2 spin liquid can be stabilized in presence of a finite J2 super-exchange, with a substantial energy gain with respect to the gapless U(1) Dirac spin liquid. However, this energy gain vanishes in the thermodynamic limit, implying that, at least within this approach, the U(1) Dirac spin liquid remains stable in a relatively large region of the phase diagram. For J2/J1 0.3, we find that a magnetically ordered state with q=0 overcomes the magnetically disordered wave functions, suggesting the end of the putative gapless spin-liquid phase.

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