Large increase of the low-frequency dielectric constant of gallium sulfide under hydrostatic pressure.

Abstract

The pressure dependence of the low-frequency dielectric constant of layered gallium sulfide, parallel to the c axis, is investigated through capacitance measurements. The measured pressure coefficient \ensuremath{\Delta}(ln${\mathrm{\ensuremath{\epsilon}}}_{\mathrm{\ensuremath{\parallel}}}$)/\ensuremath{\Delta}P is found to be (80\ifmmode\pm\else\textpm\fi{}5)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ ${\mathrm{GPa}}^{\mathrm{\ensuremath{-}}1}$. This large and positive pressure coefficient is shown to be coherent with models of charge transfer from the Ga-Ga intralayer bond to the interlayer space under pressure.