Regensburg 2013 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 7: Correlated Electrons: Spin Systems, Itinerant Magnets 1

TT 7.4: Vortrag

Montag, 11. März 2013, 10:15–10:30, H19

Spin-liquid versus spiral-order phases in the anisotropic triangular lattice — •Luca F. Tocchio¹, Hélène Feldner¹, Federico Becca², Roser Valentí¹, and Claudius Gros¹ — ¹Institut für Theoretische Physik, Goethe-Universität Frankfurt am Main, Germany — ²International School for Advanced Studies (SISSA) Trieste, Italy

We study the competition between magnetic and spin-liquid phases in the Hubbard model on the anisotropic triangular lattice, which is described by two hopping parameters t and t′ in different spatial directions and is relevant for layered organic charge-transfer salts [1]. By using a variational approach that includes spiral magnetic order, we provide solid evidence that a spin-liquid phase is stabilized in the strongly-correlated regime and close to the isotropic limit t′/t=1. Otherwise, a magnetically ordered spiral state is found, connecting the (collinear) Néel and the (coplanar) 120^∘ phases. The pitch vector of the spiral phase obtained from the unrestricted Hartree-Fock approximation is substantially renormalized in presence of electronic correlations, and the Néel phase is stabilized in a wide regime of the phase diagram, i.e., for t′/t < 0.75. We discuss these results in the context of organic charge-transfer salts.
[1] B.J. Powell and R.H. McKenzie, Rep. Prog. Phys. 74, 056501 (2011)
L.F. Tocchio, H. Feldner, F. Becca, R. Valentí, and C. Gros, arXiv:1209.1928