Superconducting digital devices can be advantageously used in future supercomputers because they can greatly reduce the dissipation power and increase the speed of operation. Non-volatile quantized states are ideal for the realization of classical Boolean logics. A quantized Abrikosov vortex represents the most compact magnetic object in superconductors, which can be utilized for creation of high-density digital cryoelectronics. In this work we provide a proof of concept for Abrikosov-vortex-based random access memory cell, in which a single vortex is used as an information bit. We demonstrate high-endurance write operation and two different ways of read-out using a spin valve or a Josephson junction. These memory cells are characterized by an infinite magnetoresistance between 0 and 1 states, a short access time, a scalability to nm sizes and an extremely low write energy. Non-volatility and perfect reproducibility are inherent for such a device due to the quantized nature of the vortex.

We probe a quantum mechanical phase rotation induced by a single Abrikosov vortex in a superconducting lead, using a Josephson junction, made at the edge of the lead, as a phase-sensitive detector. We observe that the vortex induces a Josephson phase shift equal to the polar angle of the vortex within the junction length. When the vortex is close to the junction it induces a π step in the Josephson phase difference, leading to a controllable and reversible switching of the junction into the 0-π state. This in turn results in an unusual Φ(0)/2 quantization of the flux in the junction. The vortex may hence act as a tunable "phase battery" for quantum electronics.

It has been predicted theoretically that an unconventional odd-frequency spin-triplet component of superconducting order parameter can be induced in multilayered ferromagnetic structures with non-collinear magnetization. In this work we study experimentally nano-scale devices, in which a ferromagnetic spin valve is embedded into a Josephson junction. We demonstrate two ways of in-situ analysis of such Josephson spin valves: via magnetoresistance measurements and via in-situ magnetometry based on flux quantization in the junction. We observe that supercurrent through the device depends on the relative orientation of magnetization of the two ferromagnetic layers and is enhanced in the non-collinear state of the spin valve. This provides a direct prove of controllable generation of the spin-triplet superconducting component in a ferromagnet.An interplay of superconductivity (S) and ferromagnetism (F) in hybrid S/F heterostructures leads to a variety of unusual physical phenomena [1][2][3][4][5][6][7][8][9][10]. Of particular interest is a possibility of generation of an unconventional odd-frequency spin-triplet component of the superconducting condensate [2,7]. The ferromagnetic exchange energy is usually much larger than the superconducting energy gap. Consequently, a conventional spin-singlet superconducting order parameter decays at a short range ∼ 1 nm in a spatially uniform, mono-domain ferromagnet. Experimental observations of a long-range proximity effect through strong ferromagnets [11,12] and, in particular, through almost fully spin-polarized half-metals [13][14][15] is consistent with appearance of the spin-triplet component, which is insensitive to strong magnetic and exchange fields. However, it may also be due to various types of artifacts and, at certain circumstances, a longrange spin-singlet component can be realized in clean S/F heterostructures [9]. Therefore, unambiguous confirmation for existence of the spin-triplet superconductivity in S/F heterostructures requires controllable tunability of the phenomenon. This is also prerequisite for potential applications of S/F heterostructures in spintronics.The spin-triplet order parameter in S/F heterostructures is generated in presence of an active spin-mixing interface [5,7] or in case of a spatially non-uniform distribution of magnetization [2]. The latter can be achieved in spin valve structures with several F-layers [1,3,6,[8][9][10]. Both the spin-singlet and the spin-triplet components depend on the angle between magnetization of F-layers in such superconducting spin valves. The spin-singlet component is at maximum for the antiparallel (AP) and minimum at the parallel (P) state of the spin valve [9]. The spin-triplet component is maximum at the non-collinear state with 90• misalignment between magnetic moments and zero both in P-and AP-states [3,8]. Such a behavior has been confirmed by analysis of the inverse proximity effect (i.e