Frustrated Frustration of Arrays with Four-Terminal Nb-Pt-Nb Josephson Junctions Article Swipe
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· 2025
· Open Access
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· DOI: https://doi.org/10.1103/gxdc-py56
· OA: W4415010089
We study the frustration pattern of a square lattice with fabricated Nb-Pt-Nb four-terminal Josephson junctions. The four-terminal geometry gives rise to a checkerboard pattern of alternating fluxes <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>f</a:mi></a:math>, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>f</c:mi><c:mo>′</c:mo></c:msup></c:math> piercing the plaquettes, which stabilizes the Berezinskii-Kosterlitz-Thouless transition even at irrational flux quanta per plaquette, due to an unequal repartition of integer flux sum <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>f</e:mi><e:mo>+</e:mo><e:msup><e:mi>f</e:mi><e:mo>′</e:mo></e:msup></e:math> into alternating plaquettes. This type of frustrated frustration manifests as a beating pattern of the dc resistance, with state configurations at the resistance dips gradually changing between the conventional zero- and half-flux states. Hence, the four-terminal Josephson junction array offers a promising platform to study previously unexplored flux and vortex configurations and provides an estimate on the spatial expansion of the four-terminal Josephson junction central weak link area.
