Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.6: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Anomalous magnetoresistance of a layered conductor in the weakly incoherent interlayer coupling regime — •Mark Kartsovnik¹, Dieter Andres¹, Sergei Simonov², Werner Biberacher¹, Harald Mueller³, Natalia Kushch⁴, and Ilya Sheikin⁵ — ¹Walther-Meissner-Institut, Walther-Meissner-Str. 8, 85748 Garching, Germany — ²Institute of Solid State Physics, 142432 Chernogolovka, Russia — ³ESRF, BP 220, F-38043 Grenoble, France — ⁴Institute of Problems of Chemical Physics, 142432 Chernogolovka, Russia — ⁵LNCMI, CNRS, BP 166, F-38042, Grenoble, France

Owing to a high crystal quality and an extremely weak interlayer coupling in the layered organic conductor α-(BEDT-TTF)₂KHg(SCN)₄, it is possible to realize, by selecting a sample with an appropriate electron scattering rate, either the coherent or incoherent interlayer transport regime while the strong-field criterion, ω_c τ > 1, is achieved at conventional magnetic fields of a few tesla. We report on striking differences in the angle-dependent interlayer resistance of this compound observed on samples characterized by different sample quality. In the cleanest samples, the magnetoresistance is a complex function of the magnetic field orientation, bearing the information about the geometry of the well defined three-dimensional Fermi surface. By contrast, the lower quality samples are essentially insensitive to the strength and orientation of the magnetic field component lying in the plane of the conducting layers. We attribute this anomalous behavior to the breakdown of the coherent charge transport across the layers in the lower quality samples.