Very large thermophase in ferromagnetic Josephson junctions

Abstract

The concept of thermophase refers to the appearance of a phase gradient inside a superconductor originating from the presence of an applied temperature bias across it. The resulting supercurrent flow may, in suitable conditions, fully counterbalance the temperature-bias-induced quasiparticle current therefore preventing the formation of any voltage drop, i.e., a thermovoltage, across the superconductor. Yet, the appearance of a thermophase is expected to occur in Josephson-coupled superconductors as well. Here we theoretically investigate the thermoelectric response of a thermally-biased Josephson junction based on a ferromagnetic insulator. In particular, we predict the occurrence of a very large thermophase which can reach $\pi /2$ across the contact for suitable temperatures and structure parameters, i.e., the quasiparticle thermal current can reach the critical current. Such a thermophase can be several orders of magnitude larger than that predicted to occur in conventional Josephson tunnel junctions. In order to assess experimentally the predicted very large thermophase we propose a realistic setup realizable with state-of-the-art nano fabrication techniques and well-established materials which is based on a superconducting quantum interference device. This effect could be of strong relevance in several low-temperature applications, for example, for revealing tiny temperature differences generated by coupling the electromagnetic radiation to one of the superconductors forming the junction.

4.5 pages, 4 color figures

References in corpus (5)

• Single-mode heat conduction by photons
• The Josephson heat interferometer
• Nonlocal Thermoelectric Effects and Nonlocal Onsager Relations in a Three-Terminal Proximity-Coupled Superconductor-Ferromagnet Device
• Superconductors as ideal spin sources for spintronics
• Spin-Resolved Tunneling Studies of the Exchange Field in EuS/Al Bilayers

Cited by in corpus (5)

• Revealing the magnetic proximity effect in EuS/Al bilayers through superconducting tunneling spectroscopy
• ${\theta }_0$ thermal Josephson junction
• Quasiparticle density of states and triplet correlations in superconductor/ferromagnetic-insulator structures across a sharp domain wall
• Signatures of spin-triplet Cooper pairing in the density of states of spin-textured superconductor-ferromagnet bilayers
• Thermalization of hot electrons via interfacial electron-magnon interaction