Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 68: Low-dimensional systems: Molecular conductors (TT with CPP/HL/MA/O)
HL 68.4: Vortrag
Donnerstag, 19. März 2015, 10:15–10:30, H 3010
Mott criticality in organic charge-transfer salts κ-(BEDT-TTF)2X studied by thermal expansion under He-gas pressure — •E. Gati1, R. S. Manna1, U. Tutsch1, B. Wolf1, L. Bartosch2, T. Sasaki3, H. Schubert1, J. A. Schlueter4, and M. Lang1 — 1Physikalisches Institut, Goethe Uni, SFB/TR49, D-60438 Frankfurt — 2Inst. für Theoretische Physik, Goethe Uni, D-60438 FfM — 3IMR, Tohoku University, Sendai 980577, Japan — 4Materials Science Division, National Laboratory, Argonne, Illinois 60439, USA
The Mott transition and the underlying universality class have been intensively studied in the past. The proposal of a hitherto unknown unconventional universality class for the quasi 2D organic charge-transfer salt κ-(BEDT-TTF)2Cu[N(CN)2]Cl (κ-Cl) [1], based on resistivity measurements, has attracted particular interest. In this compound, the Mott transition can be accessed by chemical pressure or the application of very small hydrostatic pressures of 300 bar. We will present measurements of the thermal expansion of κ-Cl under 4He-gas pressure [2], an unique technique, which provides a very sensitive tool to investigate critical phenomena [3,4], including effects of coupling of electrons to the crystal lattice [5]. A comparison of our results with theoretical predictions of a scaling theory [4] shows that the critical properties are incompatible with the proposed unconventional universality class.
[1] F. Kagawa et al., Nature 436, 534 (2005).
[2] R. S. Manna et al., Rev. Sci. Instrum. 83, 085111 (2012).
[3] M. de Souza et al., PRL 99, 0370031 (2007).
[4] L. Bartosch et al., PRL 104, 245701 (2010).
[5] M. Zacharias et al., PRL 109, 176401 (2012).