Electric-field-induced spin-flop in BiFeO3 single crystals at   room-temperature
  Bismuth ferrite, BiFeO3, is the only known room-temperature 'multiferroic' material. We demonstrate here, using neutron scattering measurements in high quality single crystals, that the antiferromagnetic and ferroelectric orders are intimately coupled. Initially in a single ferroelectric state, our crystals have a canted antiferromagnetic structure describing a unique cycloid. Under electrical poling, polarisation re-orientation induces a spin flop. We argue here that the coupling between the two orders may be stronger in the bulk than that observed in thin films where the cycloid is absent. 
D. Lebeugle, D. Colson, A. Forget, M. Viret, A. M. Bataille and A.   Gukasov