Pearl vortex

In superconductivity, a Pearl vortex is a vortex of supercurrent in a thin film of type-II superconductor, first described in 1964 by Judea Pearl.^[1] A Pearl vortex is similar to Abrikosov vortex except for its magnetic field profile which, due to the dominant air-metal interface, diverges sharply as 1/ $r$ at short distances from the center, and decays slowly, like 1/ $r^2$ at long distances. Abrikosov's vortices, in comparison, have very short range interaction and diverge as $log(1/r)$ near the center.

A transport current flowing through a superconducting film may cause these vortices to move with a constant velocity $v$ proportional to, and perpendicular to the transport current. Because of their proximity to the surface, and their sharp field divergence at their centers, Pearl's vortices can actually be seen by a scanning SQUID microscope.^[2]^[3]^[4] The characteristic length governing the distribution of the magnetic field around the vortex center is given by the ratio $\Lambda = 2 \lambda^2$ / $d$ , also known as "Pearl length," where $d$ is the film thickness and $\lambda$ is London penetration depth.^[5] Because this ratio can reach macroscopic dimensions (~1 mm) by making the film sufficiently thin, it can be measured relatively easy and used to estimate the density of superconducting electrons.^[4]

At distances shorter than the Pearl's length, vortices behave like a Coulomb gas (1/ $r$ repulsive force).

References

↑ Pearl, Judea (1964). "Current distribution in superconducting films carrying quantized fluxoids". Applied Physics Letters 5 (4): 65. Bibcode:1964ApPhL...5...65P. doi:10.1063/1.1754056.
↑ Tafuri, F.; J.R. Kirtley; P.G. Medaglia; P. Orgiani; G. Balestrino (2004). "Magnetic Imaging of Pearl vortices in Artificially layered $(Ba_{0.9}Nd_{0.1}CuO_{2+x})_m/(CaCuO_2)_n$ Systems". Physical Review Letters 92 (15). Bibcode:2004PhRvL..92o7006T. doi:10.1103/PhysRevLett.92.157006.
↑ Pozzi, G. (2007). "Electron optical effects of a Pearl vortex near the film edge". Physical Review B 76 (54510). Bibcode:2007PhRvB..76e4510P. doi:10.1103/PhysRevB.76.054510.
1 2 Bert, Julie A.; Beena Kalisky; Christopher Bell; Minu Kim; Yasuyuki Hikita; Harold Y. Hwang; Kathryn A. Moler (2011). "Direct imaging of the coexistence of ferromagnetism and superconductivity at the $LaAIO_3/SrTiO_3$ interface". Nature Physics 7 (10): 767––771. arXiv:1108.3150. Bibcode:2011NatPh...7..767B. doi:10.1038/nphys2079.
↑ Clem, John R. (2010). "Josephson junctions in thin and narrow rectangular superconducting strips". Physical Review B 81: 144515. arXiv:1003.0839. Bibcode:2010PhRvB..81n4515C. doi:10.1103/PhysRevB.81.144515.

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