Field-Free Superconducting Diode Effect in 45°-Twisted FeSe van der Waals Josephson Junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Iron-based superconductors like FeSe exhibit complex physics, including superconductivity and nematicity.
• The superconducting diode effect (SDE) demonstrates non-reciprocal critical current, requiring broken time-reversal symmetry (TRS) and inversion symmetry (IS).
• Existing SDE research often necessitates external magnetic fields, hindering practical applications.

Purpose of the Study:

• To investigate the possibility of a field-free superconducting diode effect in twisted FeSe Josephson junctions.
• To explore the underlying symmetry-breaking physics in iron-based superconductors.
• To assess the potential for developing novel superconducting electronic devices.

Main Methods:

• Fabrication of 45°-twisted FeSe Josephson junctions.
• Measurement of critical current dependence on bias direction and temperature.
• Analysis of the asymmetric critical current's response to magnetic field and temperature modulation.

Main Results:

• Observation of a field-free superconducting diode effect in FeSe Josephson junctions below 3 K.
• Direct evidence of SDE through the even symmetric dependence of asymmetric critical current on magnetic field.
• Suppression and polarity reversal of the SDE at 2.2 K under temperature modulation.

Conclusions:

• The study provides compelling transport evidence for a field-free SDE in iron-based superconductor FeSe.
• This finding offers a promising platform for exploring symmetry-breaking phenomena.
• The results pave the way for developing low-dissipation superconducting electronic devices without external magnetic fields.