Phase dynamics and dissipation in tunnel ferromagnetic Josephson junctions

TL;DR

This study explores the electrodynamic behavior of tunnel ferromagnetic Josephson junctions with different materials and sizes, demonstrating their potential for quantum and classical circuit integration.

Contribution

It provides a comparative analysis of Nb and Al-based ferromagnetic Josephson junctions, validating a transport model and highlighting their suitability for quantum applications.

Findings

Al-based devices show quantum phase diffusion signatures.

Transport modeling aligns well with escape dynamics.

Junction properties are consistent across different measurement methods.

Abstract

We investigate tunnel ferromagnetic Josephson junctions based on Superconductor-Insulator-thin superconductor-Ferromagnet-Superconductor multilayers. A comparative study of their electrodynamic properties is performed for junctions with niobium and aluminum (Al) electrodes, featuring different ferromagnetic interlayer materials and lateral dimensions ranging from the micrometric to the submicrometric scale. The parameters extracted from the fitting of the current-voltage characteristics using the tunnel junction microscopic model are found to be consistent with those independently estimated from switching current distribution measurements. Submicrometric Al-based devices exhibit electrodynamic properties comparable to those implemented in state-of-the-art transmon qubits and display clear signatures of quantum phase diffusion. The strong agreement between transport modelling and escape dynamics establishes a robust framework for describing hybrid ferromagnetic Josephson junctions consistent with their energy scales and supports their potential integration into superconducting quantum and classical digital circuits.