Clusters with magic numbers of vortices in rotating superfluids

Makoto Tsubota, Hideki Yoneda

M. Yu. Kagan

Григорий Ефимович Воловик

Tyler W. Neely, Guillaume Gauthier, Matthew T. Reeves +7 more

ERKOÇ, Mehmet Onur FEN and Şakir

Superfluids are characterized by absence of viscosity. When superfluids are rotated, differently from normal fluids, they form more than one vortex in the containers where they are placed. The number of vortices change as the rotation velocity changes, but this change is not linear. M.W. Zwierlein et al. observed the vortices in experiments, observing up to a number of 80. Experiments also showed that the vortex distributions cannot include large spaces. By using experimental data, we noticed that when we think of vortices as vortex rings, their centers are at the same geometric location and these geometric locations are concentric circles. We generalized the distribution of these geometric places and formulized it. Our formula includes the magic circle numbers. When the number of vortices reach these magic numbers, the number of geometric locations increase by 1.

Saad A. Khairallah, Mikhail Borisovich Sevryuk, David M. Ceperley +1 more

The interplay between magic number stabilities and superfluidity of small parahydrogen clusters with sizes N=5 to 40 and temperatures 0.5 K</=T</=4.5 K is explored with classical and quantum path integral Monte Carlo calculations. Clusters with N<26 and T</=1.5 K have large superfluid fractions even at the stable magic numbers 13, 19, and 23. In larger clusters, superfluidity is quenched especially at the magic numbers 26, 29, 32, and 37 while below 1 K, superfluidity is recovered for the pairs (27,28), (30,31), and (35,36). For all clusters superfluidity is localized at the surface and correlates with long exchange cycles involving loosely bound surface molecules.