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arXiv · 2202.05602

Comparison of the charge-crystal and charge-glass state in geometrically frustrated organic conductors studied by fluctuation spectroscopy

Tatjana Thomas·Tim Thyzel·Hungwei Sun·Kenichiro Hashimoto·Takahiko Sasaki·Hiroshi M. Yamamoto·Jens Müller
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Abstract

We present a systematic investigation of the low-frequency charge carrier dynamics in different charge states of the organic conductors $\theta$-(BEDT-TTF)$_2$$M$Zn(SCN)$_4$ with $M$=Rb,Tl, which result from quenching or relaxing the charge degrees of freedom on a geometrically frustrated triangular lattice. Due to strong electronic correlations these materials exhibit a charge-ordering transition, which can be kinetically avoided by rapid cooling resulting in a so-called charge-glass state without long-range order. The combination of fluctuation spectroscopy and a heat pulse method allows us to study and compare the resistance fluctuations in the low-resistive quenched and the high-resistive charge-ordered state, revealing striking differences in the respective noise magnitudes. For both compounds, we find strongly enhanced resistance fluctuations right at the metal-insulator transition and a broad noise maximum in the slowly cooled charge-crystal state with partly dominating two-level processes revealing characteristic activation energies.

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Tatjana Thomas, Tim Thyzel, Hungwei Sun, Kenichiro Hashimoto, Takahiko Sasaki, Hiroshi M. Yamamoto, Jens Müller. 2022-02-11. Comparison of the charge-crystal and charge-glass state in geometrically frustrated organic conductors studied by fluctuation spectroscopy. https://doi.org/10.1103/physrevb.105.205111

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