Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 72: Poster Session: Correlated Electrons

TT 72.59: Poster

Mittwoch, 14. März 2018, 15:00–19:00, Poster B

Comparative thermal expansion study on organic quantum-spin-liquid-candidate systems — •S. Hartmann¹, R. S. Manna², J. Schlueter³, Y. Yoshida⁴, and M. Lang¹ — ¹Physikalisches Institut, SFB/TR 49, Goethe-Universität Frankfurt, Germany — ²Dept. of Physics, Indian Institute of Technology Tirupati, India — ³Div. of Materials Research, National Science Foundation, Arlington, Virginia, USA — ⁴Dept. of Chemistry, Kyoto University, Japan

The search for the realization of a quantum spin-liquid (QSL) is a major concern for condensed matter physicists since its proposal in 1973. The entangled QSL ground state lacks magnetic ordering down to lowest temperatures where spins continue to fluctuate even at T = 0 K [1]. One way to experimentally realize a QSL is magnetic frustration of geometric origin, inherent to the quasi 2D-triangular lattice of the organic charge-transfer salts κ-(BEDT-TTF)₂X. We present a comparative study of ultra-high-resolution thermal expansion measurements on the QSL-candidates X = Cu₂(CN)₃ and X = Ag₂(CN)₃. The X= Cu₂(CN)₃ system shows a mysterious anomaly around 6 K, frequently assigned to a QSL instability, the origin of which is still an open question. The shape and size of this effect are attributed to a second-order phase transition [2]. In contrast, we do not find any indications for a phase transition for X= Ag₂(CN)₃. In addition, we discuss effects of applying a magnetic field and pay attention to sample-to-sample variations in the materials’ low-temperature lattice effects.
Balents, Nature 2010
Manna et al., PRL 2010