New magnetic coherence effect in superconducting La_{2-x}Sr_{x}CuO_{4}
  We have used inelastic neutron scattering to examine the magnetic fluctuations at intermediate frequencies in the simplest high temperature superconductor, La_{2-x}Sr_{x}Cu_{4}. The suppression of the low energy magnetic response in the superconducting state is accompanied by an increase in the response at higher energies. Just above a threshold energy of ~7 meV there is additional scattering present below T_{c} which is characterised by an extraordinarily long coherence length, in excess of 50 \AA. 
T.E. Mason (University of Toronto), A. Schroder (Risoe National Lab),   G. Aeppli (NEC Research), H.A. Mook (Oak Ridge), and...