Hall probe magnetometry measurements have been used to investigate the magnetic
state of various Pb microcrystals grown by electrodeposition, where careful
control of deposition parameters has allowed the tuning of their architectures.
The internal flux distribution when in the superconducting state is seen to be highly dependent on the size and geometry of the investigated samples. In nanowires single flux vortex states are seen to form, showing typical type II behaviour. As the diameter of the nanowires increases these vortex states are seen to bunch together, behaviour that begins to approach that of a type I superconductor.
Measurements of Pb triangles with sloped sides show the formation of giant vortex states typical of type I behaviour. These results also highlight the importance of geometry on surface barriers and the corresponding effect these have on flux distribution. Investigation of an icosahedron shows how symmetry effects can determine the stability of different flux states. Experimental results are in good agreement with Ginzburg-Landau calculations.
|Date of Award
|1 Apr 2010
|Simon Bending (Supervisor)