Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 71: Correlated Electrons: Poster Session

TT 71.47: Poster

Mittwoch, 18. März 2015, 15:00–18:00, Poster B

Ultrasonic investigation of GaV4S8 — •P. T. Cong1, S. Mombetsu1,2, V. Tsurkan3, A. Loidl3, S. Zherlitsyn1, and J. Wosnitza11Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany — 2Department of Physics, Hokkaido University, Japan — 3Institute of Physics, University of Augsburg, 86159 Augsburg, Germany

In recent years, transition metal-chalcogenides with the cubic GaMo4S8-type structure have attracted much interest because of their fascinating properties such as superconductivity under pressure, metal-insulator transition, 4d ferromagnetism and various structural and magnetic instabilities at low temperatures. These phenomena reflect the strong coupling of structural, electronic and magnetic degrees of freedom in this system. Here, we present results of ultrasound investigations performed on a high-quality single crystal of the tetrahedral magnetic-cluster material GaV4S8. The temperature dependence of the sound velocity and attenuation shows a huge anomaly at Ts = 44 K followed by a pronounce feature at Tc = 12.5 K related to a structural transition and ferromagnetic ordering, respectively, as known from previous magnetic-susceptibility and specific-heat results [1]. A field-induced transition at temperatures below Tc reveals a complex magnetic structure of GaV4S8, suggesting a competition of several interactions. Based on these measurements, we mapped out the BT phase diagram of GaV4S8 and discuss the role of the lattice degrees of freedom in this material.

[1] H. Nakamura et al., J. Phys.: Condens. Matter 17, 6015 (2005)

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