Effect of a magnetic field on the quasiparticle recombination in superconductors

Abstract

Quasiparticle recombination in a superconductor with an s-wave gap is typically dominated by a phonon bottleneck effect. We have studied how a magnetic field changes this recombination process in metallic thin-film superconductors, finding that the quasiparticle recombination process is significantly slowed as the field increases. While we observe this for all field orientations, we focus here on the results for a field applied parallel to the thin film surface, minimizing the influence of vortices. The magnetic field disrupts the time-reversal symmetry of the pairs, giving them a finite lifetime and decreasing the energy gap. The field could also polarize the quasiparticle spins, producing different populations of spin-up and spin-down quasiparticles. Both processes favor slower recombination; in our materials we conclude that strong spin-orbit scattering reduces the spin polarization, leaving the field-induced gap reduction as the dominant effect and accounting quantitatively for the observed recombination rate reduction.

References in corpus (6)

• Controlled vaporization of the superconducting condensate in cuprate superconductors sheds light on the pairing boson
• Spin Imbalance and Spin-Charge Separation in a Mesoscopic Superconductor
• Recombination limited energy relaxation in a BCS superconductor
• Long-range spin-polarized quasiparticle transport in mesoscopic Al superconductors with a Zeeman splitting
• Charge imbalance in superconductors in the low-temperature limit
• Spatially-resolved probing of a non-equilibrium superconductor