Search

We report on the electrical transport properties of Nb based Josephson junctions with Pt/Co 68 B 32 /Pt ferromagnetic barriers. The barriers exhibit perpendicular magnetic anisotropy, which has the main advantage for potential applications over magnetisation in-plane systems of not affecting the Fraunhofer response of the junction. In addition, we report that there is no magnetic dead layer at the Pt/Co 68 B 32 interfaces, allowing us to study barriers with ultra-thin Co 68 B 32 . In the junctions, we observe that the magnitude of the critical current oscillates with increasing thickness of the Co 68 B 32 strong ferromagnetic alloy layer. The oscillations are attributed to the ground state phase difference across the junctions being modified from zero to π . The multiple oscillations in the thickness range 0.2 ⩽ d CoB ⩽ 1.4 nm suggests that we have access to the first zero- π and π -zero phase transitions. Our results fuel the development of low-temperature memory devices based on ferromagnetic Josephson junctions. [ABSTRACT FROM AUTHOR]