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arXiv · 1311.0344

Charge-cluster glass in an organic conductor

F. Kagawa·T. Sato·K. Miyagawa·K. Kanoda·Y. Tokura·K. Kobayashi·R. Kumai·Y. Murakami
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Abstract

Geometrically frustrated spin systems often do not exhibit long-range ordering, resulting in either quantum-mechanically disordered states, such as quantum spin liquids, or classically disordered states, such as spin ices or spin glasses. Geometric frustration may play a similar role in charge ordering, potentially leading to unconventional electronic states without long-range order; however, there are no previous experimental demonstrations of this phenomenon. Here, we show that a charge-cluster glass evolves upon cooling in the absence of long-range charge ordering for an organic conductor with a triangular lattice, theta-(BEDT-TTF)2RbZn(SCN)4. A combination of time-resolved transport measurements and x-ray diffraction reveal that the charge-liquid phase has charge clusters that fluctuate extremely slowly (<10-100 Hz) and heterogeneously. Upon further cooling, the cluster dynamics freeze, and a charge-cluster glass is formed. Surprisingly, these observations correspond to recent ideas regarding the structural glass formation of supercooled liquids, indicating that a glass-forming charge liquid relates correlated-electron physics to glass physics in soft matter.

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F. Kagawa, T. Sato, K. Miyagawa, K. Kanoda, Y. Tokura, K. Kobayashi, R. Kumai, Y. Murakami. 2013-11-06. Charge-cluster glass in an organic conductor. https://doi.org/10.1038/nphys2642

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