Spin-liquid and magnetic phases in the anisotropic triangular lattice: The case of κ- (ET) 2 X

Abstract

The two-dimensional Hubbard model on the anisotropic triangular lattice, with two different hopping amplitudes t and t′, is relevant to describe the low-energy physics of κ- (ET) 2 X, a family of organic salts. The ground-state properties of this model are studied by using Monte Carlo techniques, on the basis of a recent definition of backflow correlations for strongly correlated lattice systems. The results show that there is no magnetic order for reasonably large values of the electron-electron interaction U and frustrating ratio t′ /t=0.85, suitable to describe the nonmagnetic compound with X= Cu2 (CN) 3. On the contrary, Néel order takes place for weaker frustrations, i.e., t′ /t∼0.4-0.6, suitable for materials with X= Cu2 (SCN) 2, Cu [N (CN) 2] Cl, or Cu [N (CN) 2] Br. © 2009 The American Physical Society.