Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 58: Transport: Poster Session

TT 58.33: Poster

Mittwoch, 9. März 2016, 15:00–18:30, Poster D

Transport and thermodynamic studies of the unusual metal-insulator transition in κ-(BEDT-TTF)₂Hg(SCN)₂Cl under He-gas pressure — •D. Zielke¹, E. Gati¹, S. Köhler¹, S. Winter¹, H. Schubert¹, P. Lunkenheimer², J. A. Schlueter³, and M. Lang¹ — ¹Institute of Physics, SFB/TR49, Goethe-University, Frankfurt, Germany — ²University of Augsburg, Center for Electronic Correlations & Magnetism, SFB/TR80, Germany — ³Materials Science Division, Argonne National Laboratory, USA

Organic charge-transfer salts of the BEDT-TTF family show a wide variety of electronic phases resulting from the interplay of strong on-site and inter-site Coulomb repulsion along with low dimensions. The quasi-2D κ-(BEDT-TTF)₂Hg(SCN)₂Cl is distinct by a high degree of frustration of t^′/t = 0.84 (at 50 K) [1] and reveals an unusual metal-insulator transition at T_MI = 30 K which has been associated with charge-order [2]. We present a study of dc resistance measurements at ambient and at finite hydrostatic He-gas pressure. We find that the MI transition can be rapidly shifted towards lower temperatures with increasing pressure. At P = 97 MPa the system remains metallic down to 2.4 K. In addition, our results of thermal expansion measurement show discontinuous changes of the lattice parameters at T_MI accompanied by hysteresis which prove the 1^st-order character of this transition, in contrast to literature results [3]. Moreover, we observe a glass-like transition at T_g ≈ 60-65 K which is consistent with recent calculations [4].
H. Jeschke, priv. comm.
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S. Yasin et al., Physica B 407, 1689 (2012).
Müller et al., NJP 17, 083057 (2015).