Magnetic Oscillations in A Two-Dimensional Network of Coupled Orbits

The Fermi surface of the isostructural organic metals (ET)8Hg4Cl12(C6H5X)2, where X=Cl, Br provides a two-dimensional (2D) network of compensated electron and hole quasi-2D orbits. Interlayer magnetoresistance and magnetisation of these compounds have been investigated in pulsed magnetic fields extending up to 60 and 33T, respectively. About 15 frequencies, composed of linear combinations of only three basic frequencies, are observed in the oscillatory spectra of the magnetoresistance. A quantum interferometer enclosing an area equal to the first Brillouin zone area is evidenced and consistently accounted for by the conventional 2D Lifshits–Kosevich model. If this model formally accounts for almost all of the observed oscillatory components, it fails to give consistent quantitative data in most other cases which points to the unconventional nature of these oscillations.