Superconducting piezoelectric effect
The magnetopiezoelectric effect (MPE) is a cross-coupling between an electric current and strain in metals with neither inversion symmetry nor time-reversal symmetry. Unlike the conventional piezoelectric effect, the MPE allows a piezoelectric response in superconductors, as we call the superconducting piezoelectric effect (SCPE). The SCPE may enable a piezoelectric response without Joule heating and provide a probe of exotic superconducting symmetry. In this paper, we propose a formulation of the SCPE and calculate both the MPE and SCPE in the two-dimensional noncentrosymmetric s-wave superconductor under an in-plane magnetic field. We find that the magnitude of the SCPE is comparable to the MPE. It is also clarified that finite total momentum of Cooper pairs in the helical superconducting state plays a crucial role in the SCPE.