Pressure Dependence of Mg2Sn Electrical Resistance

Abstract

AbstractThe electrical resistivity of single crystal Mg2Sn 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 X3 and X1 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 X3 and X1 bands with respect to the Γ15 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 Γ15— X1 energy derivatives with respect to pressure. The existence of a third conduction band, with an energy location of 0.075 eV above the X3 band at zero pressure and having a pressure rate of +6 × 10−6 eV/bar with respect to the Γ15 band, is suggested but not definitely established by a slight upward curvature of the resistance vs. pressure data below 7 kbar.