First order phase transition from the vortex liquid to an amorphous   solid
  We present a systematic study of the topology of the vortex solid phase in superconducting Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$ samples with low doses of columnar defects. A new state of vortex matter imposed by the presence of geometrical contours associated with the random distribution of columns is found. The results show that the first order liquid-solid transition in this vortex matter does not require a structural symmetry change. 
M. Menghini, Yanina Fasano, F. de la Cruz, S.S. Banerjee, Y.   Myasoedov, E. Zeldov, C. J. van der Beek, M. Konczykowski and...