The ϕ Josephson junction has a doubly degenerate ground state with the Josephson phases ±ϕ. 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.

The tunneling anisotropic magnetoresistance (TAMR) of single Co atoms adsorbed on a double-layer Fe film on W(110) is observed by scanning tunneling spectroscopy. Without applying an external magnetic field the TAMR is found by comparing spectra of atoms that are adsorbed on the domains and domain walls of the Fe film. The TAMR can be as large as 12% and repeatedly changes sign as a function of bias voltage. First-principles calculations show that the hybridization between Co d states of different orbital symmetries depends on the magnetization direction via spin-orbit coupling. This leads to an anisotropy of the density of states and thus induces a TAMR.

The 0–π transition in Superconductor-Insulator-superconductor-Ferromagnet-Superconductor (SIsFS) Josephson junctions (JJs) was investigated experimentally. As predicted by theory, an s-layer inserted into a ferromagnetic SIFS junction can enhance the critical current density up to the value of an SIS tunnel junction. We fabricated Nb′ | AlOx | Nb | Ni60Cu40 | Nb JJs with wedge-like s (Nb) and F (Ni60Cu40) layers and studied the Josephson effect as a function of the s- and F-layer thickness, ds and dF, respectively. For ds = 11 nm, π-JJs with SIFS-type jc(dF) and critical current densities up to jcπ=60 A/cm2 were obtained at 4.2 K. Thicker ds led to a drastic increase of the critical current decay length, accompanied by the unexpected disappearance of the 0–π transition dip in the jc(dF) dependence. Our results are relevant for superconducting memories, rapid single flux quantum logic circuits, and solid state qubits.

The spin polarization of the tunneling current between a Cr-covered scanning tunneling microscope tip and a Fe-covered W(110) surface was controllably modified by transferring single Cr atoms from the tip to the surface. Reproducible reversal of the spin polarization enables the discrimination of magnetic from electronic properties without the need of an external magnetic field.

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