
 Tuning magnetic and bond order in the cuprate superconductors 
  Given the picture of competing orders and quantum phase transitions in the cuprate superconductors (reviewed in S. Sachdev, Science 288, 475 (2000); condmat/0009456), it is natural to search for an external parameter which will tune systems across such transitions. 
  In strongly typeII superconductors like the cuprates, above a small lower critical field, a magnetic field perpendicular to the layers induces a triangular lattice of vortices: superconductivity is completely suppressed in the very small vortex cores, and these are surrounded by regions of superflow of Cooper pairs (see Figure 3 below). 
  Spin and charge order in the vortex lattice of the cuprates: experiment and theory, S. Sachdev, Developments in Mathematical and Experimental Physics, Volume B: Statistical Physics and Beyond, A. Macias, F. Uribe, and E. Diaz eds, Kluwer Academic, New York (2002); condmat/0203363. 
 qpt.physics.harvard.edu /superflow.html (1817 words) 
