Mott Transition in a Valence Bond Solid Insulator with a Triangular Lattice

TL;DR

This study explores the Mott transition in a spin-frustrated triangular lattice insulator under pressure and magnetic field, revealing a valence bond solid phase and anomalous resistivity behavior in the metallic state.

Contribution

It provides new insights into the phase diagram of a frustrated Mott insulator, highlighting the presence of a valence bond solid phase near superconductivity and unique resistivity characteristics.

Findings

Valence bond solid phase neighbors superconducting and metallic phases.

Resistivity in metallic phase follows a T^{2.5} dependence.

Phase diagram profile resembles that of antiferromagnetic Mott insulators.

Abstract

We have investigated the Mott transition in a quasi-two-dimensional Mott insulator EtMe$_3$P[Pd(dmit)$_2$]$_2$ with a spin-frustrated triangular lattice in hydrostatic pressure and magnetic field. In the pressure-temperature ($P$-$T$) phase diagram, a valence bond solid phase is found to neighbor the superconductor and metal phases at low temperatures. The profile of the phase diagram is common to those of Mott insulators with antiferromagnetic order. In contrast to the antiferromagnetic Mott insulators, the resistivity in the metallic phase exhibits anomalous temperature dependence, $\rho = \rho_0 + A T^{2.5}$.