Spontaneous and persistent currents in superconductive and mesoscopic structures (Review Article)

• Date: 2004
• Main Author: Kulik, I.O.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2004
• Subjects: Сверхпроводимость и мезоскопические структуры
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/119787
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Spontaneous and persistent currents in superconductive and mesoscopic structures (Review Article) / I.O. Kulik // Физика низких температур. — 2004. — Т. 30, № 7-8. — С. 705-713. — Бібліогр.: 79 назв. — англ.

We briefly review aspects of superconductive persistent currents in Josephson junctions of the
 S/I/S, S/O/S and S/N/S types, focusing on the origin of jumps in the current versus phase
 dependences, and discuss in more detail the persistent as well as «spontaneous» currents in the
 Aharonov–Bohm mesoscopic and nanoscopic (macromolecular) structures. A fixed-number-of-electrons
 mesoscopic or macromolecular conducting ring is shown to be unstable against structural
 transformation removing spatial symmetry (in particular, azimuthal periodicity) of its electron-
 lattice Hamiltonian. In case when the transformation is blocked by strong coupling to an external
 azimuthally symmetric environment, the system becomes bistable in its electronic configuration
 at certain number of electrons. At such a condition, the persistent current has a nonzero value
 even at the (almost) zero applied Aharonov–Bohm flux, and results in very high magnetic susceptibility
 dM/dH at small nonzero fields, followed by an oscillatory dependence at larger fields.
 We tentatively assume that previously observed oscillatory magnetization in cyclic metallo-organic
 molecules by Gatteschi et al. can be attributed to persistent currents. If this proves correct,
 it may open an opportunity (and, more generally, macromolecular cyclic structures may suggest
 the possibility) of engineering quantum computational tools based on the Aharonov–Bohm effect
 in ballistic nanostructures and macromolecular cyclic aggregates.