Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Poster Session Correlated Electrons 2

TT 47.7: Poster

Mittwoch, 18. März 2020, 15:00–19:00, P2/3OG

Drastic change of the charge carrier dynamics at the Mott metal-insulator transition in κ-(BETS)2Mn[N(CN)2]3 — •Yassine Agarmani1, Tatjana Thomas1, Mark Kartsovnik2, Nataliya Kushch3, and Jens Müller11Institute of Physics, Goethe University Frankfurt, Germany — 2Walther-Meißner-Institut, Bayerische Akademie der Wissenschaft, Germany — 3Institute of Problems of Chemical Physics, Russian Academy of Sciences, Russia

The quasi-two-dimensional organic conductor κ-(BETS)2Mn[N(CN)2]3 combines strong electronic correlations with magnetic properties dominated by the presence of magnetic Mn2+ ions in the insulating polymeric anion layers. The system undergoes a superstructure transition near 102 K, presumably of structural origin, and a metal-insulator transition at TMI∼30 K likely associated with a Mott instability [1,2]. In order to investigate the dynamical properties of the charge carriers, fluctuation (noise) spectroscopy has proven to be a successful method by measuring the time-dependent fluctuations of a sample’s resistance [3]. In this compound the normalized noise power spectral density shows a broad maximum at ∼100 K and a dramatic increase below TMI. The increase is accompanied by non-Gaussian fluctuations indicated by time-dependent noise spectra. In contrast, above TMI there is a good agreement with a simple model assuming independent fluctuators allowing to determine characteristic energies. We discuss our results in light of the possibilities of electronic ferroelectricity, recently observed in a number of dimer-Mott insulators.

[1] JACS 130, 7238 [2] PRB 82, 155123 [3] Crystals 8, 166

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