Fast vortex dynamics and relaxation times in NbRe-based heterostructures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Superconducting heterostructures are crucial for advanced electronic devices.
• Understanding Abrikosov vortex dynamics is key to controlling superconducting properties.
• Comparing normal metal (S/N) and ferromagnetic (S/F) interfaces reveals unique behaviors.

Purpose of the Study:

• To investigate Abrikosov vortex dynamics and flux-flow instabilities in NbRe/Au (S/N) and NbRe/Py (S/F) bilayers.
• To compare the critical velocities and quasiparticle energy relaxation times between S/N and S/F heterostructures.
• To assess the potential of these heterostructures for applications requiring fast relaxation processes.

Main Methods:

• Fabrication of NbRe/Au and NbRe/Py heterostructures using sputtering.
• Characterization via electrical transport measurements, including I-V characteristics.
• Analysis of flux-flow instability within the Larkin-Ovchinnikov framework.

Main Results:

• NbRe/Py bilayers demonstrated higher vortex critical velocities compared to NbRe/Au bilayers.
• Quasiparticle energy relaxation times were extracted: ~150 ps for NbRe/Au and ~24 ps for NbRe/Py.
• NbRe/Py bilayers showed relaxation times one order of magnitude smaller than reported for NbRe microbridges.

Conclusions:

• NbRe/Py (S/F) heterostructures exhibit enhanced vortex dynamics and significantly faster quasiparticle energy relaxation compared to NbRe/Au (S/N) counterparts.
• The observed properties suggest NbRe/Py bilayers are promising for developing devices that rely on rapid relaxation phenomena.
• These findings contribute to the fundamental understanding of S/F interfaces in superconductivity and their technological implications.