Münster 1999 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 15: Postersitzung II: Elektronische Eigenschaften (1-12), Josephson-Kontakte (13-27), Heavy Fermions (28-40), Theorie HTSL (41-48), M-I-Überg
änge, Korrelierte Systeme (49-79)
TT 15.1: Poster
Mittwoch, 24. März 1999, 14:30–18:00, Foy
Fermi surface studies on the org. supercond. κ -ET2Cu[N(CN)2]Br — •H. Weiss1, M. V. Kartsovnik2, W. Biberacher2, E. Steep1, E. Balthes1, A.G.M. Jansen1, K. Andres2, and N. Kushch2 — 1High Magnetic Field Laboratory, MPI-FKF/CNRS, BP 166, F-38042 Grenoble Cedex 9 — 2Walther-Meissner-Inst., Walther-Meissner-Str. 8, D-85748 Garching
Measurements of the interlayer magnetotransport of the organic superconductor κ -(BEDT-TTF)2Cu[N(CN)2]Br have been carried out at ambient pressure as well as under quasi- hydrostatic pressure up to 12 kbar [1,2]. Shubnikov-de Haas (SdH) oscillations at frequencies ≈ 150, 300, and 3900 T have been observed at various pressures. The rapid oscillations correspond to 100% of the Brillouin zone cross-section area, revealing a magnetic breakdown orbit in accordance with the theoretically predicted Fermi surface. The lower two frequencies do not agree with the theoretical predictions. To interpret this discrepancy, we propose that the Fermi surface undergoes substantial topological changes at a superstructural transition below 200 K. Ambient pressure Haas-van Alphen studies on the same compound revealed the magnetic breakdown-frequency, as it was seen in the SdH experiment. Another frequency, F≈ 540 T, is detected which coincides with the theoretical predictions. The low frequency oscillations, seen in the SdH experiments under high pressure, have not been observed.
[1] H.Weiss et al., JETP Lett. 66, 202 (1997)
[2] H. Weiss et al., submitted to Phys. Rev. B