Giant viscoelasticity near Mott criticality in PbCrO3 with large lattice anomalies

TL;DR

This study reveals giant viscoelastic effects near the Mott critical point in PbCrO3, highlighting a complex coupling between lattice elasticity and electron viscosity that influences the critical behavior.

Contribution

It uncovers the role of giant viscoelasticity as a hidden degree of freedom in Mott criticality, advancing understanding of charge-lattice coupling in correlated materials.

Findings

Large lattice anomalies near Mott criticality in PbCrO3

Giant viscoelasticity governs the critical behavior

Lattice behavior deviates from existing universality classes

Abstract

Coupling of charge and lattice degrees of freedom in materials can produce intriguing electronic phenomena, such as conventional superconductivity where the electrons are mediated by lattice for creating supercurrent. The Mott transition, which is a source for many fascinating emergent behaviors, is originally thought to be driven solely by correlated electrons with an Ising criticality. Recent studies on the known Mott systems have shown that the lattice degree of freedom is also at play, giving rise to either Landau or unconventional criticality. However, the underlying coupling mechanism of charge and lattice degrees of freedom around the Mott critical endpoint remains elusive, leading to difficulties in understanding the associated Mott physics. Here we report a study of Mott transition in cubic PbCrO3 by measuring the lattice parameter, using high-pressure x-ray diffraction techniques. The Mott criticality in this material is revealed with large lattice anomalies, which is governed by giant viscoelasticity that presumably results from a combination of lattice elasticity and electron viscosity. Because of the viscoelastic effect, the lattice of this material behaves peculiarly near the critical endpoint, inconsistent with any existing university classes. We argue that the viscoelasticity may play as a hidden degree of freedom behind the Mott criticality.