Stabilizing the metallic state in a quasi-two-dimensional (ET)$_{8}$Hg$_{4}$Br$_{12}$(C$_{6}$H$_{5}$Cl)$_{2}$ organic metal under a pressure of 6 kbar

A quasi-two-dimensional (ET)$_{8}$Hg$_{4}$Br$_{12}$(C$_{6}$H$_{5}$Cl)$_{2}$ organic metal undergoes the metal–dielectric transition at $T\sim$ 90 K upon cooling. An external pressure of $P\sim$ 6 kbar completely recovers the metallic state and makes it possible to observe the Shubnikov–de Hass oscillations with a frequency of $F\approx$ 215 T and a cyclotron mass of $m^*\approx$ 0.95 $m_0$. The behavior of the oscillations is consistent with the Fermi surface representation in the form of electron and hole orbits covering the same areas of the first Brillouin zone.