A boomerang-shaped reduction in interlayer phase coherence in Bi ₂Sr₂CaCu₂0_8+y with splayed columnar defects

We present evidence for entangled solid vortex matter in a glassy state in a layered superconductor Bi2Sr2CaCu2O 8+y containing randomly splayed linear defects. The interlayer phase coherence(IPC) - probed by the Josephson plasma resonance - is enhanced at high temperatures, reflecting the recoupling of vortex liquid by the defects. At low temperatures in the vortex solid state, the interlayer coherence follows a boomerang-shaped reentrant temperature path with an unusual low field decrease in coherence, indicative of meandering vortices. This behavior suggests strongly suppressed IPC in this system, which may be explained by the vortex entanglement induced by the columnar defects in the "splayed-glass" state. © 2009 IOP Publishing Ltd.