Observation of enhanced fluctuation diamagnetism in lanthanum   superconductors with dilute magnetic impurities
  The fluctuation-induced diamagnetism (FD), associated with the presence of precursor Cooper pairs in the normal state, has been measured in lanthanum with dilute magnetic (Pr) and nonmagnetic (Lu) impurities. It is found that while for pure La and La-Lu alloys the FD agrees, as expected, with the theoretical predictions, it is much larger for La-Pr alloys (around a factor 5 for La-2at.%Pr). These results suggest the existence of an indirect contribution to the FD arising from the interaction between fluctuating Cooper pairs and magnetic impurities. 
Felix Soto, Lucia Cabo, Jesus Mosqueira, Manuel V. Ramallo, Jose A.   Veira and Felix Vidal