Spontaneous emergence of Josephson junctions in homogeneous rings of single-crystal Sr<inf>2</inf>RuO<inf>4</inf>

Abstract

Funder: JSPS-EPSRC Core-to-Core program (A. Advanced Research Network)Funder: JSPS research fellow (KAKENHI Grant No. JP16J10404)Funder: Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organisation for Scientific Research); doi: https://doi.org/10.13039/501100003246Funder: Grant-in-Aid JSPS KAKENHI JP26287078 and JP17H04848AbstractThe chiral p-wave order parameter in Sr2RuO4 would make it a special case amongst the unconventional superconductors. A consequence of this symmetry is the possible existence of superconducting domains of opposite chirality. At the boundary of such domains, the locally suppressed condensate can produce an intrinsic Josephson junction. Here, we provide evidence of such junctions using mesoscopic rings, structured from Sr2RuO4 single crystals. Our order parameter simulations predict such rings to host stable domain walls across their arms. This is verified with transport experiments on loops, with a sharp transition at 1.5 K, which show distinct critical current oscillations with periodicity corresponding to the flux quantum. In contrast, loops with broadened transitions at around 3 K are void of such junctions and show standard Little–Parks oscillations. Our analysis demonstrates the junctions are of intrinsic origin and makes a compelling case for the existence of superconducting domains.</jats:p

    Similar works