Pressure Dependence of Mg 2 Sn Electrical Resistance

The electrical resistivity of single crystal Mg 2 Sn is measured as a function of hydrostatic pressure to 29 kbar at 298 °K and 27 kbar at 320 °K. Various p‐type samples with varying mobilities and mobility‐temperature dependences are analysed. The results for pressures less than seven kbar may be described by a simple valence‐conduction band model with an energy gap pressure dependence of +4.75 × 10 −6 eV/bar. The results for pressures up to 29 kbar are described by a two conduction band model. The second conduction band is shown to be important even at low pressures; almost 10% of the conduction electrons are in the upper band at room pressure and temperature. The bottom and top conduction bands are identified as X 3 and X 1 bands respectively. The energy separation between these two bands is deduced to be 0.130 eV at zero pressure. The least‐squares pressure coefficients of the X 3 and X 1 bands with respect to the Γ 15 valence band are measured to be +4.75 × 10 −6 eV/bar and — 0.90 × 10 −6 eV/bar, respectively. Estimated correction for a systematic error, introduced by the mobility dependence on pressure through the decrease of carrier lifetime when interband scattering increases, suggests that +4.75 × 10 −6 eV/bar and—0.75 × 10 −6 eV/bar may be better values for the Γ 15 — X 1 energy derivatives with respect to pressure. The existence of a third conduction band, with an energy location of 0.075 eV above the X 3 band at zero pressure and having a pressure rate of +6 × 10 −6 eV/bar with respect to the Γ 15 band, is suggested but not definitely established by a slight upward curvature of the resistance vs. pressure data below 7 kbar.