Magnetic coupling through flux branching of adjacent type-I and -II superconductors in a neutron star

Abstract

The inner and outer cores of neutron stars are believed to contain type-I and -II proton superconductors, respectively. The type-I superconductor exists in an intermediate state, comprising macroscopic flux-free and flux-containing regions, while the type-II superconductor is flux-free, except for microscopic, quantized flux tubes. Here, we show that the inner and outer cores are coupled magnetically, when the macroscopic flux tubes subdivide dendritically into quantized flux tubes, a phenomenon called flux branching. An important implication is that ∼1012 (r1/106) up to of energy are required to separate a quantized flux tube from its progenitor macroscopic flux tube, where is the length of..