Quasiparticle Trapping In Three Terminal Ferromagnetic Tunneling Devices

摘要

Hybrid Superconductor/Ferromagnet structures have been investigated recentlyto address the interplay between ferromagnetism and superconductivity. Theyalso open up new routes for the investigation of out of equilibriumsuperconductivity. Here, we show how it is possible for out of equilibriumexcitations produced in a superconducting thin film (S) to be localized in aferromagnetic trap (F). Specifically, a ferromagnetic nano-volume in goodcontact with S represents a potential well for the quasiparticles (QPs) at thegap edge. As the superconducting proximity effect is highly suppressed in F,QPs get efficiently trapped and they share their energy with the free electronsin the trap. The electronic temperature Te in the trap can be increased by upto 60% from the bath temperature at 320 mK as measured by tunnelingspectroscopy using a second junction.