Superconducting transition temperature of the equiatomic ZrNb alloy at pressures to 56.4GPa

The superconducting transition temperature of the equiatomic ZrNb alloy is measured in dependence on pressure to 56.4GPa. The Tc(P) dependence is found to achieve a maximum around 42GPa and to have an anomalous behavior with a shallow minimum in the pressure range 5-10GPa. This behavior of Tc(P) is similar to that earlier observed on pure metal Nb. A comparison with recent model calculations suggests that the features of the Tc(P) behavior both in pure Nb and in the ZrNb alloy are of the same nature and result from the high-pressure anomalies in their phonon spectra.