Fermi surface shape and angle-dependent magnetoresistance oscillations

Abstract

The shape of the Fermi surface of organic metals can be measured by recording angle-dependent magnetoresistance oscillations. We review this technique and develop a model for parametrizing the shape of the quasi-two-dimensional Fermi surface sections which often appear in organic metals. Using this model, we show that it is possible to extract more detail about the quasi-two-dimensional pocket shape from angle-dependent magnetoresistance oscillations than in the traditional approximation which assumes an elliptical Fermi surface shape. We also consider the implications for cyclotron resonance experiments.

Quasi-two-dimensional organic superconductors: A review

“…The low scattering rates in quasi-two-dimensional organic superconductors mean that it is possible to use a range of techniques to make accurate measurements of the Fermi-surface topology. The experimental techniques have been described in other reviews [1,6,13,31,32,33]. We shall mention a few of the more important examples.…”

“…Whilst they give very accurate information about the cross-sectional areas of the Fermi-surface sections, magnetic quantum oscillations do not provide any details of their shape. Such information is usually derived from angle-dependent magnetoresistance oscillations (AMROs) [1,6,32,33]. AMROs are measured by rotating a sample in a fixed magnetic field whilst monitoring its resistance; the coordinate used to denote the position of AMROs is the polar angle θ between the normal to the sample's quasi-two-dimensional planes and the magnetic field [32,33].…”

Test for Interlayer Coherence in a Quasi-Two-Dimensional Superconductor

“…• it seems that the observed peak width is sometimes dominated by closed orbits on the Q1D sheets, and sometimes by those on the Q2D FS section; the dominant width presumably depends on which FS section is more effective at averaging v ⊥ [19]. MMW studies [9] suggest that the interlayer corrugations of the Q1D sheets are more complex than those given by Eqn.…”

“…The edges of Fig. 2 are dominated by AMROs and related phenomena; as these are well known [5,19,25] in κ-(BEDT-TTF) 2 Cu(NCS) 2 [8], we shall not describe them further in this paper. Close to θ = 90…”

Thermal Activation between Landau Levels in the Organic Superconductorβ′′−(BEDT−TTF)2Nam1, Ardavan2, Symington3 et al. 2001Phys. Rev. Lett.278481View full textAdd to dashboardCite

“…Angle-dependent magnetoresistance oscillation (AMRO) [8,10] and millimetre-wave magnetoconductivity experiments [11] show that the cross-section of this Q2D pocket resembles an elongated diamond. The same experimental techniques find no evidence for the presence of Q1D Fermi sheets at low temperatures [8,10,11], unlike the situation in other Q2D organic metals [3]. By contrast, in order to explain the observation of a fixed chemical potential µ in the dHvA effect [7], Wosnitza et al proposed Q1D states which have an enormous density of states, exceeding the estimates from bandstructure calculations by at least an order of magnitude [7].…”