Dresden 2003 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 11: Postersitzung II (Metall-Isolator-Überg
änge, Phasenüberg
änge in Quantensystemen, Theorie: Systeme korrelierter Elektronen)

TT 11.13: Poster

Dienstag, 25. März 2003, 14:30–19:00, P2c, P2d

Superposition of the orbital quantization and Pauli effect in a charge-density-wave organic conductor α-(BEDT-TTF)₂KHg(SCN)₄ — •Mark Kartsovnik¹, Dieter Andres¹, Werner Biberacher¹, and Pavel Grigoriev² — ¹Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meissner-Str. 8, 85748 Garching — ²L.D. Landau Institute for Theoretical Physics, 142432 Chernogolovka, Russia

The organic metal α-(BEDT-TTF)₂KHg(SCN)₄ undergoes a charge-density-wave (CDW) transition at T_c ≈ 8.5 K. Under a strong magnetic field the CDW₀ groundstate is suppressed due to the Pauli (spin-splitting) effect and a new phase, CDW_x, with a field-dependent CDW wavevector Q(B) is established. The critical field of the CDW₀ → CDW_x transition, B_k, decreases with tilting the field away from the direction perpendicular to the highly conducting layers. At high tilt angles 65^∘<θ < 90^∘ the resistivity and magnetization exhibit, with sweeping the field above B>B_k, a hysteretic structure reminiscent of a series of first order transitions. We propose this behavior to be caused by a novel manifestation of the orbital quantization effect on Q(B) under the conditions when the nesting of the Fermi surface is deteriorated by the Pauli effect.