Unconventional critical behaviour in a quasi-two-dimensional organic conductor

Abstract

Changing the interactions between particles in an ensemble-by varying the temperature or pressure, for example-can lead to phase transitions whose critical behaviour depends on the collective nature of the many-body system. Despite the diversity of ingredients, which include atoms, molecules, electrons and their spins, the collective behaviour can be grouped into several families (called 'universality classes') represented by canonical spin models1. One kind of transition, the Mott transition2, occurs when the repulsive Coulomb interaction between electrons is increased, causing wave-like electrons to behave as particles. In two dimensions, the attractive behaviour responsible for the superconductivity in high-transition temperature copper oxide3,4 and organic5-7 compounds appears near the Mott transition, but the universality class to which two-dimensional, repulsive electronic systems belongs remains unknown. Here we present an observation of the critical phenomena at the pressure-induced Mott transition in a quasi-two-dimensional organic conductor using conductance measurements as a probe. We find that the Mott transition in two dimensions is not consistent with known universality classes, as the observed collective behaviour has previously not been seen. This peculiarity must be involved in any emergent behaviour near the Mott transition in two dimensions.

10 pages, 3 figures

References in corpus (3)

• Quantum Mott Transition and Multi-Furcating Criticality
• Quantum Mott Transition and Superconductivity
• Ginzburg-Landau Theory and Classical Critical Phenomena of Mott Transition

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• Kondo proximity effect: How does a metal penetrate into a Mott insulator?
• Exact diagonalization study of Mott transition in the Hubbard model on an anisotropic triangular lattice
• Quasiparticles at the verge of localization near the Mott metal-insulator transition in a two-dimensional material
• Anomalous Lattice Response at the Mott Transition in a Quasi-2D Organic Conductor
• Universality of liquid-gas Mott transitions at finite temperatures
• Field-induced staggered magnetic moment in the quasi-two-dimensional organic Mott insulator $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2$]Cl
• A novel non-Fermi-liquid state in the iron-pnictide FeCrAs
• Kramers degeneracy in a magnetic field and Zeeman spin-orbit coupling in antiferromagnets
• Non-local correlations in metals close to a charge order insulator transition
• Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets
• Quantum critical "opalescence" around metal-insulator transitions
• Variational Monte Carlo Study of Electron Differentiation around Mott Transition
• Antiferromagnetic Spin Fluctuations in the Metallic Phase of Quasi-Two-Dimensional Organic Superconductors
• Mott transition and superconductivity in the strongly correlated organic superconductor $\kappa$-(BEDT-TTF)${}_2$Cu[N(CN)${}_2]$Br
• Competition between magnetism and superconductivity in the organic metal $\kappa$-[BEDT-TTF]${}_2$Cu[N(CN)${}_2$]Br
• Magnetic Field-Induced Superconductor-Insulator-Metal Transition in an Organic Conductor: An Infrared Magneto-Optical Imaging Spectroscopy