title: Recombination-limited energy relaxation in a Bardeen-Cooper-Schrieffer superconductor.
abstract: We study quasiparticle energy relaxation at subkelvin temperatures by injecting hot electrons into an Al island and measuring the energy flux from quasiparticles into phonons both in the superconducting and in the normal state. The data show strong reduction of the flux at low temperatures in the superconducting state, in qualitative agreement with the theory for clean superconductors. However, quantitatively the energy flux exceeds the theoretical predictions both in the superconducting and in the normal state, suggesting an enhanced or additional relaxation process.
authors.affiliation: Low Temperature Laboratory, Helsinki University of Technology, P.O. Box 3500, 02015 TKK, Finland.
authors.forename: A V
authors.initials: AV
authors.lastname: Timofeev
authors.forename: C Pascual
authors.initials: CP
authors.lastname: García
authors.forename: N B
authors.initials: NB
authors.lastname: Kopnin
authors.forename: A M
authors.initials: AM
authors.lastname: Savin
authors.forename: M
authors.initials: M
authors.lastname: Meschke
authors.forename: F
authors.initials: F
authors.lastname: Giazotto
authors.forename: J P
authors.initials: JP
authors.lastname: Pekola