Fraunhofer Spectra in the Chiral Helimagnet Cr_1/3NbS₂

Josephson junctions with magnetic barriers provide an experimental opportunity to probe the interaction between superconductivity and ferromagnetism, showing phenomena such as a pair correlation function that oscillates in space. A related, but relatively unexplored, interaction is that between superconductivity and a chiral magnetic system, where the spins of the magnet form spirals, rather than all pointing in the same direction. Such systems could show spontaneous pinned vortices, as well as vortex currents, and even p-wave superconductivity. In this experiment we fabricate Josephson junctions using the chiral helimagnet Cr_1/3NbS₂, and measure hysteretic and asymmetric Fraunhofer patterns, as well as unexpectedly large critical currents.