Localised Wannier orbital basis for the Mott insulators GaV4S8 and GaTa4Se8

Abstract

We study the electronic properties of GaV4S8 (GVS) and GaTaSe8 (GTS), two distant members within the large family of chalcogenides AM4X8, with A={Ga, Ge}, M={V, Nb, Ta, Mo} and X={S, Se}. While all these compounds are Mott insulators, their ground state show many types of magnetic order, with GVS being ferromagnetic and GTS non-magnetic. Based on their bandstructures, calculated with Density Functional Theory methods, we compute an effective tight binding Hamiltonian in a localised Wannier basis set, for each one of the two compounds. The localised orbitals provide a very accurate representation of the bandstructure, with hopping amplitudes that rapidly decrease with distance. We estimate the super-exchange interactions and show that the Coulomb repulsion with the Hund's coupling may account the for the different ground states observed in GVS and GTS. Our localised Wannier basis provides a starting point for realistic Dynamical Mean Field Theory studies of strong correlation effects in this family compounds.

arXiv comment5 pages, 5 figures

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Cited by in corpus (7)

• Spin-orbital Entangled Molecular $j_{\mathrm{eff}}$ States in Lacunar Spinel Compounds
• First-Order Insulator-to-Metal Mott Transition in the Paramagnetic 3D System GaTa4Se8
• Molecular Mott state in the deficient spinel GaV${}_4$S${}_8$
• Lattice dynamics and electronic excitations in a large family of lacunar spinels with a breathing pyrochlore lattice structure
• Bond Ordering and Molecular Spin-Orbital Fluctuations in the Cluster Mott Insulator GaTa${}_4$Se${}_8$
• Novel $J_{\mathrm{eff}}$=3/2 Metallic Phase and Unconventional Superconductivity in GaTa${}_4$Se${}_8$
• Optical, dielectric, and magnetoelectric properties of ferroelectric and antiferroelectric lacunar spinels