Browsing by Author "Bezryadin, Alexey"

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Interference, diffraction, and diode effects in superconducting array based on bismuth antimony telluride topological insulator
(2023-12) Song, Xiangyu; Suresh Babu, Soorya; Bai, Yang; Golubev, Dmitry S.; Burkova, Irina; Romanov, Alexander; Ilin, Eduard; Eckstein, James N.; Bezryadin, Alexey
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
It is well-known in optics that the spectroscopic resolution of a diffraction grating is much better compared to an interference device having just two slits, as in Young’s famous double-slit experiment. On the other hand, it is well known that a classical superconducting quantum interference device (SQUID) is analogous to the optical double-slit experiment. Here we report experiments and present a model describing a superconducting analogue to the diffraction grating, namely an array of superconducting islands positioned on a topological insulator film Bi0.8Sb1.2Te3. In the limit of an extremely weak field, of the order of one vortex per the entire array, such devices exhibit a critical current peak that is much sharper than the analogous peak of an ordinary SQUID. Therefore, such arrays can be used as sensitive absolute magnetic field sensors. A key finding is that the device acts as a superconducting diode, controlled by magnetic field.
Superconducting phase transition in inhomogeneous chains of superconducting islands
(2020-10-02) Ilin, Eduard; Burkova, Irina; Song, Xiangyu; Pak, Michael; Golubev, Dmitri S.; Bezryadin, Alexey
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We study one-dimensional chains of superconducting islands with a particular emphasis on the regime in which every second island is switched into its normal state, thus forming a superconductor-insulator-normal metal (S-I-N) repetition pattern. As is known since Giaever tunneling experiments, tunneling charge transport between a superconductor and a normal metal becomes exponentially suppressed, and zero-bias resistance diverges, as the temperature is reduced and the energy gap of the superconductor grows larger than the thermal energy. Here we demonstrate that this physical phenomenon strongly impacts transport properties of inhomogeneous superconductors made of weakly coupled islands with fluctuating values of the critical temperature. We observe a nonmonotonous dependence of the chain resistance on both temperature and magnetic field, with a pronounced resistance peak at temperatures at which some but not all islands are superconducting. We explain this phenomenon by the inhomogeneity of the chains, in which neighboring superconducting islands have slightly different critical temperatures. We argue that the Giaever's resistance divergence can also occur in the zero-temperature limit. Such quantum transition can occur if the magnetic field is tuned such that it suppresses superconductivity in the islands with the weaker critical field, while the islands with stronger energy gap remain superconducting. In such a field, the system acts as a chain of S-I-N junctions.