Regensburg 2019 – wissenschaftliches Programm
MA 6.14: Vortrag
Montag, 1. April 2019, 18:30–18:45, Theater
Thermal expansion studies on the spin-liquid candidate system κ-(BEDT-TTF)2Ag2(CN)3 — •S. Hartmann1, E. Gati2, Y. Yoshida3, G. Saito4, and M. Lang1 — 1Physikalisches Institut, SFB/TR 49, Goethe-Uni Frankfurt, Germany — 2Ames Laboratory, Iowa State University, USA — 3Division of Chemistry, Kyoto University, Japan — 4Toyota Physical and Chemical Research Institute, Nagakute, 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 state lacks magnetic ordering down to lowest temperatures where spins continue to fluctuate even at T = 0 K . 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, known as weak Mott insulators. We present results of ultra-high-resolution thermal expansion measurements on the newly-synthesized QSL-candidate system X = Ag2(CN)3. Our main finding includes pronounced broad extrema in the thermal expansion coefficient at T ∼ 18 K along all three crystallographic directions which we assign to the effect of strong electronic correlations. The observed anomalies are qualitatively consistent with theoretical results based on the Hubbard model on a triangular lattice . The directional anisotropy of the anomalies implies a ratio of the hopping integrals t’/t < 1.
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