Effects of Stress on Superconducting Sn, In, Tl, and Al

Hydrostatic pressures of 0 to 100 atmos obtained with helium gas pressure, and of 1.9×{}10³ atmos obtained by an ice expansion bomb technique are used to measure the pressure displacement of critical temperature Tc. The coefficient (∂Tc∂p) for Sn, In, Tl, and Al is -4.7±{}0.2, -4.0±{}0.2, +0.6±{}0.3, and -2.0±{}0.2 in units of 10^-5 ^∘{}K/atmos, respectively. The temperature dependence of R=(∂Hc∂p)T(∂Hc∂p)_Tc above 1^∘{}K is described by R=0.61+0.029T² for Sn, and R=0.77+0.020T² for In. This result is discussed in connection with the similarity principle, H₀Tc=constant. From an analysis combining stress and isotope effects, it is seen that Tc, or Hc, is more sensitive to volume changes, holding zero-point lattice vibration amplitude fixed, than to zero-point amplitude changes, holding V fixed: ${({{∂}{H}c}{{∂}lnV})}_{{q}²}=5.5×{}{({{∂}{H}c}{{∂}ln{q}²})}V$ for Sn. Zero-pressure critical field data are also presented for the subject metals.