SKM 2023 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 66: Cryogenic Detectors

TT 66.5: Talk

Friday, March 31, 2023, 10:45–11:00, HSZ 304

Fluxon counters and velocimeters at superconducting strips — •Oleksandr Dobrovolskiy — University of Vienna, Faculty of Physics, Nanomagnetism and Magnonics, SuperSpin Laboratory

Thin strips with large critical current Ic are required for superconducting microstrip single-photon detectors (SMSPDs) [1] and Cherenkov generators/detectors of spin waves by ultra-fast moving fluxons [2]. In this regard, high Ic implies blocking of the penetration of vortices via the strip edges and their control via material and edge-barrier engineering [3]. Thus, at sufficiently large transport currents Itr, a slit at the edge of a superconducting strip acts as a gate for the vortices entering into it. These vortices form a jet, which is narrow near the slit and expands due to the repulsion of vortices as they move to the opposite edge of the strip, giving rise to a transverse voltage Vp. In my talk, I will present our experimental results on voltage kinks in the I-V curves which occur each time the number of fluxons crossing the strip is increased by one [4]. I will also dwell on the appearance of the non-monotonic Vp in MoSi strips with slits milled by FIB at various distances from the transverse voltage leads [5]. Our findings are relevant for the performance of SMSPDs and superconducting devices operated in the single-fluxon regime.
[1] Korneeva et al., PRAppl. 13, 024011 (2020)
[2] Dobrovolskiy et al., arXiv:2103.10156
[3] Budinska et al., PRAppl. 17, 034072 (2021)
[4] Bevz et al., submitted
[5] Bezuglyj et al., PRB 105, 214507 (2022)