Temperature dependence of structural and electronic properties of the spin-liquid candidate kappa-(BEDT-TTF)2Cu2(CN)3

TL;DR

This study examines how temperature variations influence the crystal structure and electronic properties of the spin-liquid candidate kappa-(BEDT-TTF)2Cu2(CN)3, revealing significant changes in the Hubbard model parameters.

Contribution

It provides a detailed analysis of temperature-dependent structural and electronic changes in a spin-liquid material using X-ray diffraction and theoretical modeling.

Findings

Temperature significantly affects the Hubbard parameters.

Electronic frustration and interaction strength vary with temperature.

Structural symmetry remains unchanged despite electronic property changes.

Abstract

We investigate the effect that the temperature dependence of the crystal structure of a two dimensional organic charge-transfer salt has on the low-energy Hamiltonian representation of the electronic structure. For that, we determine the crystal structure of kappa-(BEDT-TTF)2Cu2(CN)3 for a series of temperatures between T=5 K and 300 K by single crystal X-ray diffraction and analyze the evolution of the electronic structure with temperature by using density functional theory and tight binding methods. We find a considerable temperature dependence of the corresponding triangular lattice Hubbard Hamiltonian parameters. We conclude that even in the absence of change of symmetry, the temperature dependence of quantities like frustration and interaction strength can be significant and should be taken into account.