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Nonlinear electronic transport in the anomalous metallic state of quasi‐2D organic superconductors κ‐(BEDT‐TTF) 2 X
Author(s) -
Rommel R.,
Hartmann B.,
Brandenburg J.,
Schlueter J. A.,
Müller J.
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201200901
Subject(s) - condensed matter physics , superconductivity , joule heating , electrical resistivity and conductivity , mott insulator , materials science , ohmic contact , nonlinear system , resistor , physics , voltage , nanotechnology , layer (electronics) , quantum mechanics , composite material
We present measurements of the first‐ and third‐harmonic voltage response in ac electronic transport measurements, representing the linear (ohmic) and nonlinear resistivity, respectively, of the quasi‐two‐dimensional (2D) organic superconductors κ‐(BEDT‐TTF) 2 X. Nonlinear transport is a sensitive tool to probe the microgeometry of the electronic system in high‐quality single crystals. For the title compounds, the normalconducting metallic state in the vicinity of the Mott metal–insulator (MI) transition and critical endpoint is known to be highly unusual. Our results reveal large current‐induced intrinsic inhomogeneities, at high current densities most pronounced at the so‐called T * anomaly, which characterizes the anomalous metallic state. The observed nonlinearities in the interlayer transport do not depend on frequency and cannot be ascribed to a simple Joule heating mechanism in a resistor network. Furthermore, we find evidence supporting the notion of electronic phase separation induced by the Mott critical endpoint. The observed dependence of the generated third‐harmonic voltage on the current density reveals a systematic behavior suggesting that current‐induced electronic inhomogeneities are more pronounced for more strongly correlated systems.