Half - h/2e - Oscillations of SQUIDs

TL;DR

This paper reports the fabrication of SQUIDs exhibiting oscillations with half the usual flux quantum period, suggesting novel underlying physics such as a strong sin(2φ) component or Cooper-pair interactions.

Contribution

It introduces bicrystal SQUIDs with half-flux quantum oscillations, indicating new phenomena in Josephson junction behavior.

Findings

SQUIDs modulate with a period of half the flux quantum

Characteristics suggest a strong sin(2φ) component or quartet interactions

Potential implications for understanding Cooper-pair interactions

Abstract

The current-voltage characteristics of Superconducting Quantum Interference Devices (SQUIDs) are known to modulate as a function of applied magnetic field with a period of one flux quantum $\Phi_0=h$/2e. Here we report on the fabrication and properties of SQUIDs modulating with a period of $1/2\times\Phi_0$. The characteristics of these bicrystal SQUIDs are consistent with either a strong sin(2$\phi$) component of the current-phase relation of the Josephson current, or with an interaction between the Cooper-pairs, causing an admixture of quartets to the condensate.