Direct Observation of the Transition from the Conventional Superconducting State to the π State in a Controllable Josephson Junction

J. J. A. Baselmans; T. T. Heikkilä; B. J. van Wees; T. M. Klapwijk

doi:10.1103/PhysRevLett.89.207002

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Direct Observation of the Transition from the Conventional Superconducting State to the π State in a Controllable Josephson Junction

J. J. A. Baselmans, T. T. Heikkilä, B. J. van Wees, T. M. Klapwijk

DOI 10.1103/PhysRevLett.89.207002 · Physical Review Letters

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Abstract

We measure the full supercurrent-phase relation of a controllable π junction around the transition from the conventional 0 state to the π state. We show that around the transition the Josephson supercurrent-phase relation changes from Isc≃Icsin(φ) to Isc≃Icsin(2φ). This implies that, around the transition, two minima in the junction free energy exist, one at φ=0 and one at φ=π, whereas only one minimum exists at the 0 state (at φ=0) and at the π state (at φ=π). Theoretical calculations based on the quasiclassical theory are in good agreement with the observed behavior.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Nb Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
YBa2Cu3O7-x Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown