Triangular lattices of these structures can be formed in Type II superconductors near the upper critical field, owing to the instability of these structures for winding numbers greater than 1. For 10 points each:
[10m] Name these structures, whose winding number describes the phase change around a loop containing these structures. In order to keep the wavefunction single valued, it must go to zero at the cores of these circulating structures.
ANSWER: vortices [accept vortex; prompt on topological defects]
[10h] Those lattices of vortices close to the upper critical field are named for this Soviet physicist who researched Type II superconductors. This physicist also pioneered QFT methods in condensed matter theory, and codiscovered gapless superconductivity.
ANSWER: Alexei Abrikosov
[10e] Abrikosov lattices are often experimentally realised in these systems, named for a German and an Indian physicist. This so-called ‘fifth state of matter’ requires a very low temperature to realise, and sees a macroscopic occupation of the ground state.
ANSWER: Bose-Einstein Condensate