Special Colloquium

Vortices in Nature: from Black Holes and Hurricanes to Superconductors

Victor V. Moshchalkov
INPAC-Institute for Nanoscale Physics and Chemistry
Katholieke Universiteit Leuven, Belgium

*Monday, September 4, 2006   4:30 p.m.  NSH 118

(Refreshments at 4:00 p.m. NSH 118)

 

A remarkable variety of seemingly very different phenomena will be discussed: black holes, hurricanes, whirlpools, twisted light, superconducting levitation, etc. At the same time these phenomena are all related to something which does unite them – to vortices. After an introductory tour into general physics of classical vortices, the focus will shift towards quantized vortices in superconductors and more specifically in nano-superconductors.  Superconductivity is a remarkable example of macroscopic quantum phenomena. It exists only below the critical surface in the space of the three variables: temperature – magnetic field – current. Superconducting condensate is confined by the sample boundaries, very much like the wave function is confined by the walls of a quantum box. Through the optimisation of the confinement, the superconducting critical parameters can be substantially improved. This concept of nanostructuring is applied systematically to control and manipulate the behaviour of vortices in different nanostructured superconductors. Vortex ratchets and their similarity with self-propelled liquid droplets will be also discussed. Lateral nanostructuring can in fact create such conditions for the vortex pinning by huge arrays of nanofabricated antidots or magnetic dots which maximize also the second important superconducting critical parameter - critical current- up to its theoretical limit - depairing current. It implies that “quantum design” of the two important superconducting critical parameters - critical current and critical field – is not a dream but a reality.

*Note different day, time and location.