Quantum oscillations in a novel organic quasi-two-dimensional (BEDO-TTF) 5 [RbHg(SCN) 4 ] 2 metal
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Quantum Oscillations in a Novel Organic Quasi-Two-Dimensional (BEDO-TTF)5[RbHg(SCN)4]2 Metal R. B. Lyubovskiœa, b, c, S. I. Pesotskiœa, b, c, *, J. A. A. J. Perenboomc, E. I. Zhilyaevaa, O. A. Bogdanovaa, and R. N. Lyubovskayaa a
Institute of Problems in Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow oblast, 142432 Russia *e-mail: [email protected] b International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw, 53-421 Poland c Nijmegen High Filed Magnet Laboratory, Nijmegen, 6525 ED the Netherlands Received January 6, 2007
Abstract—Quantum magnetization and magnetoresistance oscillations are detected in the quasi-two-dimensional organic metal (BEDO-TTF)5[RbHg(SCN)4]2 for the first time. The magnetization oscillation spectrum corresponds to a calculated Fermi surface provided that a magnetic breakdown is realized. The magnetoresistance oscillation spectrum contains additional frequencies, one of which can unambiguously be related to quantum interference. An analysis of the angular dependence of the magnetoresistance oscillation amplitude indicates that the many-body interactions in this metal are weak. PACS numbers: 71.18.+y, 72.20.My DOI: 10.1134/S1063776108060137
1. INTRODUCTION The Fermi surface of all quasi-two-dimensional organic metals based on ET (bis(ethylenedithio)tetrathiafulvalene) and its derivatives represents a weakly corrugated cylinder with its axis normal to conducting layers. Depending on the filling of the conduction band and the specific features of carrier transfer in the conducting layers, the section of the Fermi surface by a plane parallel to these layers can have several different shapes [1]. One of these sections is shown in Fig. 1; it belongs to the organic quasi-two-dimensional metal (BEDO-TTF)5[CsHg(SCN)4]2 (BEDO is bis(ethylenedioxy)) [2]. This Fermi surface is qualitatively similar to the Fermi surfaces characteristic of the crystal lattices of the so-called α-, κ-, and θ-type structures. These structures have the following common feature: the translation of the initial oval Fermi surface, whose area coincides with the first Brillouin zone area, onto the entire reciprocal lattice leads to the formation of closed hole pockets with an area of about 20% of the Brillouin zone area and open electron orbits. In crystals with inversion centers, the gap between the pockets and open sheets is virtually absent. In some metals that have no inversion center, e.g., (BEDO-TTF)5[CsHg(SCN)4]2, this gap is several millielectron volts and can be overcome in reasonable magnetic fields, which results in a magnetic breakdown [3]. Thus, coherent chains of magneticbreakdown orbits appear in organic metals with a Fermi surface of the described type. Such chains can exhibit a wide spectrum of quantum magnetoresistance and magnetization oscillations of various origins. For
example, in (BEDO-TTF)5[CsHg(SCN)4]2, we [2] detected Shubnikov–de Haas oscillations, which were caused by carrier motion in closed pockets and closed magnetic-breakdown orbits, an
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