Evidence for Intra-Unit-Cell magnetic order in Bi2Sr2CaCu2O8+d
  Polarized elastic neutron scattering measurements have been performed in the bilayer copper oxide system Bi2Sr2CaCu2O8+d, providing evidence for an intra unit cell (IUC) magnetic order inside the pseudo-gap state. That shows time reversal symmetry breaking in that state as already reported in Bi2Sr2CaCu2O8+d through dichroism in circularly polarized photoemission experiments. The magnetic order displays the same characteristic features as the one previously reported for monolayer HgBa2CuO4+d and bilayer YBa2Cu3O6+x, demonstrating that this genuine phase is ubiquitous of the pseudo-gap of high temperature copper oxide materials. 
S. De Almeida-Didry, Y. Sidis, V. Baledent, F. Giovannelli, I.   Monot-Laffez and P. Bourges
cond-mat.supr-con