N. Ruppelt | Searcharxiv

arXiv2014

The effect of normal metal layers in ferromagnetic Josephson junctions

Using the Usadel equation approach, we provide a compact formalism to calculate the critical current density of 21 different types of ferromagnetic (F) Josephson junctions containing insulating (I) and normal metal (N) layers in the weak link regions. In particular, we obtain that even a thin additional N layer may shift the 0-$π$ transitions to larger or smaller values of the thickness $d_F$ of the ferromagnet, depending on its conducting properties. For certain values of $d_F$, a 0-$π$ transition can even be achieved by changing only the N layer thickness. We use our model to fit experimental data of SIFS and SINFS tunnel junctions, where S is a superconducting electrode.

cond-mat.supr-con↗

arXiv2013

Memory cell based on a $φ$ Josephson junction

The $φ$ Josephson junction has a doubly degenerate ground state with the Josephson phases $\pmφ$. We demonstrate the use of such a $φ$ Josephson junction as a memory cell (classical bit), where writing is done by applying a magnetic field and reading by applying a bias current. In the "store" state, the junction does not require any bias or magnetic field, but just needs to stay cooled for permanent storage of the logical bit. Straightforward integration with Rapid Single Flux Quantum logic is possible.

cond-mat.supr-con↗