Superconducting quantum interference effect in NbSe₂/NbSe₂van der Waals junctions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Layered materials exhibit exotic superconducting and ferromagnetic properties.
• Van der Waals (vdW) stacking enables fabrication of novel junction structures with clean interfaces.
• Niobium diselenide (NbSe2) vdW Josephson junctions demonstrate high supercurrent transparency.

Purpose of the Study:

• To investigate the behavior of NbSe2/NbSe2 vdW junctions under in-plane magnetic fields.
• To characterize the observed voltage drop oscillations and their dependence on temperature and magnetic field.
• To elucidate the underlying physical mechanism responsible for the oscillations.

Main Methods:

• Fabrication of NbSe2/NbSe2 vdW junctions.
• Measurement of voltage drop across the junction under varying in-plane magnetic fields and temperatures.
• Analysis of oscillation characteristics, including magnitude and temperature dependence.

Main Results:

• Observation of periodic voltage drop oscillations across NbSe2/NbSe2 vdW junctions in an in-plane magnetic field.
• The oscillation magnitude exhibits non-monotonic temperature dependence, increasing with temperature initially.
• These features distinguish the oscillations from standard Josephson junction critical current modulation and the Little-Parks effect.

Conclusions:

• The observed oscillations are attributed to quantum interference between two superconducting junctions within the vdW interface.
• This phenomenon provides a pathway for developing in-plane superconducting quantum interference devices (SQUIDs).
• The proposed device leverages the Ising-pairing nature of NbSe2 and can operate under high magnetic fields.