Josephson junctions are the building blocks of superconducting electronics, with well-established applications in precision metrology and quantum computing. Fabricating a Josephson junction has been a resource-intensive and multistep procedure, involving lithography and wet-processing, which are not compatible with many applications. Here, we introduce a fully additive direct-write approach, where a scanning electron microscope can print substrate-conformal Josephson devices in a matter of minutes, requiring no additional processing. The junctions are made entirely by electron-beam-induced deposition (EBID) of tungsten carbide. We utilize EBID-tunable material properties to write, in one go, full proximity junctions with superconducting electrodes and metallic weak links and tailor their Josephson coupling. The Josephson behavior of these junctions is established and characterized by their microwave-induced Shapiro response and field-dependent transport. Our efforts provide a versatile and nondestructive alternative to conventional nanofabrication and can be expanded to print three-dimensional superconducting sensor arrays and quantum networks.

The investigation of the transport properties of single molecules by flowing tunneling currents across extremely narrow gaps is relevant for challenges as diverse as the development of molecular electronics and sequencing of DNA. The achievement of well-defined electrode architectures remains a technical challenge, especially due to the necessity of high precision fabrication processes and the chemical instability of most bulk metals. Here, we illustrate a continuously adjustable tunneling junction between the edges of two twisted graphene sheets. The unique property of the graphene electrodes is that the sheets are rigidly supported all the way to the atomic edge. By analyzing the tunneling current characteristics, we also demonstrate that the spacing across the gap junction can be controllably adjusted. Finally, we demonstrate the transition from the tunneling regime to contact and the formation of an atomic-sized junction between the two edges of graphene.

The chiral p-wave order parameter in Sr2RuO4 would make it a special case amongst the unconventional superconductors. A consequence of this symmetry is the possible existence of superconducting domains of opposite chirality. At the boundary of such domains, the locally supressed condensate can produce an intrinsic Josephson junction. Here, we provide evidence of such junctions using mesoscopic rings, structured from Sr2RuO4 single crystals. Our order parameter simulations predict such rings to host stable domain walls across their arms. This is verified with transport experiments on loops, with a sharp transition at 1.5 K, which show distinct critical current oscillations with periodicity corresponding to the flux quantum. In contrast, loops with broadened transitions at around 3 K are void of such junctions and show standard Little-Parks oscillations. Our analysis demonstrates the junctions are of intrinsic origin and makes a compelling case for the existence of superconducting domains. seems probable, domains or edge currents have not been observed directly. Indications for their existence, however, have been found in transport experiments, which utilize Ru inclusions to form proximity junctions between Sr2RuO4 and a conventional s-wave superconductor [10,11]. A complication in the physics of Sr2RuO4 is that breaking of the tetragonal crystal symmetry due to Ru inclusions or a uniaxial strain can induce a different superconducting state with an enhanced superconducting transition temperature ≈ 3 K [13,14]. Recent experiments suggest that this so-called 3-K phase may exhibit a non-chiral state with a single-component order parameter [15,16]. In this paper, we refer to the multicomponent phase with of around 1.5 K, associated with the pure bulk limit, as the "intrinsic phase" and the possible single-component phase, characterized by ≈ 3 K, as the "extrinsic phase".The vast majority of experiments in the past two decades have been limited to bulk crystals, typically hundreds of microns in dimension. This is partly due to the unavailability of superconducting Sr2RuO4 films. The chiral domains, however, are expected to be no more than a few microns in size [5,11]. Moreover, the time-dependent switching noise observed in transport measurements suggests the domains are mobile [10,11]. We note here that the role of chiral domains resulting in hysteretic behaviour has been discussed in the Bi-Ni bilayer system [12]. The arbitrary configuration of the domains introduces an element of uncertainty.On the other hand, the energy cost associated with a chiral domain wall (ChDW), grows per area [17]. It has been recently discussed that mesoscopic samples made of chiral p-wave superconductors could host multichiral states [18,19], where the two ± chiral components are divided into superconducting domains, separated by ChDWs. This makes mesoscopic structures a promising platform to verify and potentially control the domains.

Since the discovery of the long-range superconducting proximity effect, the interaction between spin-triplet Cooper pairs and magnetic structures such as domain walls and vortices has been the subject of intense theoretical discussions, while the relevant experiments remain scarce. We have developed nanostructured Josephson junctions with highly controllable spin texture, based on a disk-shaped Nb/Co bilayer. Here, the vortex magnetization of Co and the Cooper pairs of Nb conspire to induce long-range triplet (LRT) superconductivity in the ferromagnet. Surprisingly, the LRT correlations emerge in highly localized (sub-80 nm) channels at the rim of the ferromagnet, despite its trivial band structure. We show that these robust rim currents arise from the magnetization texture acting as an effective spin–orbit coupling, which results in spin accumulation at the bilayer–vacuum boundary. Lastly, we demonstrate that by altering the spin texture of a single ferromagnet, both 0 and π channels can be realized in the same device.