Luca Fausto Tocchio
International School for Advanced Studies, Italy
Title: Ferroelectricity and magnetism in the organic charge transfer salts κ-(ET)2X
Biography
Biography: Luca Fausto Tocchio
Abstract
The molecular conductors κ-(ET)2X, where ET denotes an organic molecule and X is an anion, exhibit electronic ferroelectricity, where charge order breaks inversion symmetry, accompanied by the onset of magnetic order. These materials can be modeled by a 3/4 filled extended Hubbard model on a two-orbital anisotropic triangular lattice (see figure), where the molecular degrees of freedom are explicitly taken into account. The model is theoretically investigated by the variational Monte Carlo method. By studying the effect of the competing inter-site Coulomb interactions, we determine charge order patterns and how these charge orders generate emergent magnetic order. In particular, we find three charge ordered phases, namely, a nonpolar insulating one, a polar insulating one, leading to ferroelectricity, and a charge-ordered metallic phase with a 3-fold geometry. The charge ordered phases are accompanied by the presence of magnetic order that is more enhanced within the polar phase.
Recent Publications
1.R Kaneko, L F Tocchio, R Valentí, C Gros (2016) Emergent lattices with geometrical frustration in doped extended Hubbard models, Phys. Rev. B 94, 195111.
2.E Ghorbani, L F Tocchio, F Becca (2016) Variational wave functions for the S=1/2 Heisenberg model on the anisotropic triangular lattice: Spin liquids and spiral orders, Phys. Rev. B 93: 085111.
3.L F Tocchio, C Gros, X F Zhang, S Eggert (2014) Phase diagram of the triangular extended Hubbard model. Phys. Rev. Lett. 113: 246405.
4. L F Tocchio, H Feldner, F Becca, R Valentí, C Gros (2013) Spin-liquid versus spiral-order phases in the anisotropic triangular lattice. Phys. Rev. B 87: 035143.
