Observation of Landau-Type Branching in the Intermediate State

Abstract

In the original form of Landau’s ¹ theory of the intermediate state macroscopic superconducting and normal laminae were assumed to emerge from the interior of the specimen metal more or less unchanged apart from a spreading out of the normal laminae when approaching the metal surface. However, since the local field is equal to H _c , on the interface, the field in the middle of a normal lamina must drop below H _c , when it spreads out. This led Landau to the development of a branching model² in which the normal laminae were supposed to split first into two, then four laminae, etc., becoming finely divided as they approached the surface of the superconductor. An alternative system of branched threads, rather than laminae, was considered by Andrew³ in an attempt to explain the restoration of resistance to a superconducting cylinder in a transverse field.

Research Studentship from the Science Research Council.