Effect of large uniaxial stress on the superconducting transition temperature of zinc and cadmium

"Whiskers" of Zn and Cd can support large elastic stress (\ensuremath{\sim} 8 kbar). We have measured the change in the superconducting transition temperature ${T}_{c}$ with stress $\ensuremath{\sigma}$ in these whiskers. In Cd we find ${(\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}\ensuremath{\sigma}})}_{\ensuremath{\sigma}=0}$ to be 3.7 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ K ${\mathrm{m}}^{2}$/N for stress parallel to the hexagonal axis, and -0.46 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ K ${\mathrm{m}}^{2}$/N for stress perpendicular to the hexagonal axis. For Zn, ${(\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}{\ensuremath{\sigma}}_{\ensuremath{\parallel}}})}_{\ensuremath{\sigma}=0}$ was measured to be 5.1 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ K ${\mathrm{m}}^{2}$/N and ${(\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}{\ensuremath{\sigma}}_{\ensuremath{\perp}}})}_{\ensuremath{\sigma}=0}$ was -1.0 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}10}$ K ${\mathrm{m}}^{2}$/N. An anomalous relation between ${T}_{c}$ and $\ensuremath{\sigma}$ was found in Cd and is attributed to changes in Fermi-surface topology at high stress. As in other materials the large anisotropy in $\frac{\ensuremath{\partial}{T}_{c}}{\ensuremath{\partial}\ensuremath{\sigma}}$ in Cd and Zn can be explained by anisotropies in the stress dependence of the lattice and electronic properties.

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