Measurements on Quantized Vortex Lines with Singular or Continuous Core Structurein Rotating (3)He-A

摘要

3He-A is the most unusual example of superfluids in which different topologicallystable quantized vortices exist. Among them are vortex lines with singular or continuous core structure. The doubly quantized continuous vortex is the prevailing type, which is observed in most experiments on the routing state. In this case vorticity is concentrated into the soft core. The singular vortex has a hard core, in which the order parameter deviates from its bulk value. In 3He-A singular vortices are treated during a slow cool-down through Tc under rotation, when the superfluid sample settles into its minimum energy state. At temperatures T < 0.99Tc, continuous vortices have the lowest critical velocity of nucleation and are created first when rotation is started. The different structures of vorticity can be identified from the cw NMR spectrum: A satellite appears, in addition to bulk liquid peak, with a characteristic frequency shift and intensity for each type of vorticity.