AbstractWe report on the electrical transport properties of Nb based Josephson junctions with Pt/Co$$_{68}$$
68
B$$_{32}$$
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$$_{68}$$
68
B$$_{32}$$
32
interfaces, allowing us to study barriers with ultra-thin Co$$_{68}$$
68
B$$_{32}$$
32
. In the junctions, we observe that the magnitude of the critical current oscillates with increasing thickness of the Co$$_{68}$$
68
B$$_{32}$$
32
strong ferromagnetic alloy layer. The oscillations are attributed to the ground state phase difference across the junctions being modified from zero to $$\pi $$
π
. The multiple oscillations in the thickness range $$0.2~\leqslant ~d_\text {CoB}~\leqslant ~1.4$$
0.2
⩽
d
CoB
⩽
1.4
nm suggests that we have access to the first zero-$$\pi $$
π
and $$\pi $$
π
-zero phase transitions. Our results fuel the development of low-temperature memory devices based on ferromagnetic Josephson junctions.
Zero-Phase-Difference Josephson Current Based on Spontaneous Symmetry Breaking via Parametric Excitation of a Movable Superconducting Dot
