Determination of the Fermi velocity by angle-dependent periodic orbit resonance measurements in the organic conductor alpha-(BEDT-TTF)(2)KHg(SCN)(4)

Article

关键词: MAGNETORESISTANCE OSCILLATIONS;    TRIPLET SUPERCONDUCTIVITY;    SEMICLASSICAL DESCRIPTION;    CYCLOTRON-RESONANCE;    DENSITY-WAVE;    SURFACE;    MAGNETOTRANSPORT;    TRANSPORT;    FIELD;    FLUCTUATION;   

DOI  :  10.1103/PhysRevB.66.134513

来源: SCIE

【 摘 要 】

We report on detailed angle-dependent studies of the microwave (nu = 50-90 GHz) interlayer magnetoelectrodynamics of a single crystal sample of the organic charge-density-wave (CDW) conductor alpha-(BEDT-TTF)(2)KHg(SCN)(4). Recently developed instrumentation enables both magnetic-field (B) sweeps for a fixed sample orientation and angle sweeps at fixed nu/B. We observe series' of resonant absorptions, which we attribute to periodic orbit resonances (POR)-a phenomenon closely related to cyclotron resonance. The angle dependence of the POR indicates that they are associated with the low-temperature quasi-one-dimensional (Q1D) Fermi surface (FS) of the title compound; indeed, all of the resonance peaks collapse onto a single set of nu/B versus angle curves, generated using a semiclassical magnetotransport theory for a single Q1D FS. We show that Q1D POR measurements provide one of the most direct methods for determining the Fermi velocity, without any detailed assumptions concerning the band structure; our analysis yields an average value of upsilon(F) = 6.5 x 10(4) m/s. Quantitative analysis of the POR harmonic content indicates that the Q1D FS is strongly corrugated. This is consistent with the assumption that the low-temperature FS derives from a reconstruction of the high-temperature quasi-two-dimensional FS, caused by the CDW instability. Detailed analysis of the angle dependence of the POR yields parameters associated with the CDW superstructure, which are consistent with published results. Finally, we address the issue as to whether or not the interlayer electrodynamics are coherent in the title compound. We obtain a relaxation time from the POR linewidths, which is considerably longer than the interlayer hopping time, indicating that the transport in this direction is coherent.

【 授权许可】

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