Publication Date:
2016-12-09
Description:
The Mott metal-insulator transition, a paradigm of strong electron-electron correlations, has been considered as a source of intriguing phenomena. Despite its importance for a wide range of materials, fundamental aspects of the transition, such as its universal properties, are still under debate. We report detailed measurements of relative length changes L / L as a function of continuously controlled helium-gas pressure P for the organic conductor -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl across the pressure-induced Mott transition. We observe strongly nonlinear variations of L / L with pressure around the Mott critical endpoint, highlighting a breakdown of Hooke’s law of elasticity. We assign these nonlinear strain-stress relations to an intimate, nonperturbative coupling of the critical electronic system to the lattice degrees of freedom. Our results are fully consistent with mean-field criticality, predicted for electrons in a compressible lattice with finite shear moduli. We argue that the Mott transition for all systems that are amenable to pressure tuning shows the universal properties of an isostructural solid-solid transition.
Electronic ISSN:
2375-2548
Topics:
Natural Sciences in General
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