Pancake vortex molecules in HgBa2Ca−1Cu O (n⩾ 6) superconductors

HgBa 2 Ca n −1 Cu n O y (Hg:12( n − 1) n ) phases have the same T c independent of n and the same vortex melting line for n ⩾ 6. In these materials, there are two types of pancake pairs: those separated by the thick block of ( n − 2) inner CuO 2 planes, which are weakly coupled by the magnetic interaction, and, respectively, those separated by the thin HgBa 2 O x charge reservoir layer, which are much stronger coupled by the Josephson coupling. The vortex melting line common to all Hg:12( n − 1) n phases ( n ⩾ 6), separates two new vortex phases, pancake-molecule-glass, and pancake-molecule-liquid.