Josephson Junctions and NanoSQUIDs Grown by Focused Electron and Ion Beam Induced Deposition

Focused Electron and Ion Beam Induced Deposition (FEBID and FIBID, respectively) are direct-write resist-free nanolithography techniques enabling the growth of high-resolution nano- and micro-structures. They rely on a gas precursor that is injected into the area of interest and decomposed by a focused electron or ion beam. Using the W(CO)₆ precursor and Ga⁺ or He⁺ FIBID [1], we grow superconducting in-plane nanowires with high lateral resolution [2], as well as three-dimensional superconducting nanostructures [3]. In this contribution, we will present recent results on the fabrication of Josephson junctions and nanoSQUIDs based on FIBID- and FEBID-grown W-C deposits. First, results of W-C nanoSQUIDs patterned as two large pads connected by two short nanowires will be shown. In these devices, the critical current oscillates as a function of the externally-applied magnetic field, which results in a large output voltage to magnetic flux change (1.3 mV per magnetic flux quantum) [4]. Interestingly, these nanoSQUIDs can be implemented on a cantilever for application in scanning-SQUID technology [5]. Other experiments in which Josephson Junctions (JJs) are created with alternative geometries and also with FEBID will be shown here. In summary, FEBID and FIBID represent techniques that can be exploited for the direct-write fabrication of superconducting devices for application in quantum technologies [6].<br/>[1] P. Orús, F. Sigloch, S. Sangiao, J.M. De Teresa, Nanomaterials 12 (2022) 1367<br/>[2] P. Orús, R. Córdoba, G. Hlawacek, J.M. De Teresa, Nanotechnology 32 (2021) 085301<br/>[3] R. Córdoba et al., Nano Letters 19 (2019) 8597<br/>[4] F. Sigloch, P. Orús, S. Sangiao, J.M. De Teresa, Nanoscale Advances 4 (2022) 4628<br/>[5] M. Wyss et al., Phys. Rev. Appl. 17 (2022) 034002<br/>[6] J. M. De Teresa, Materials in Quantum Technology 3 (2023) 013001