Some science treats from the lab


A perfect superconductor

  Have you ever seen a measured magnetization loop without ANY hysteresis? We have not... until recently. In July 2006, Jake Hoberg made a lead sphere by casting molten lead. Here is the actual measurement taken with a Quantum Design MPMS on 12 July 2006:
  Apparently, this is a textbook example. Not only there is NO hysteresis, but it also follows exactly what is expected for of a superconducting sphere with demagnetization factor N=1/3. Now, the big question is - what is the topology of the intermediate state in that sphere? Our answer is - flux tubes, but Landau thought otherwise...