BiFeO₃ is a multiferroic materials in which ferroelectric and anti-ferromagnetic orders coexist well above room temperature (T_N=643 K, T_C=1093 K), with a high polarization (over 100 μC/cm² [1]). We have shown at the LLB by neutron diffraction that these two order parameters interact and that the magnetization of the material can be modified by the application of an electric field. This opens the way towards the implementation of this material in spintronic devices in which magnetization could be controlled by a small electrical voltage rather than by currents or magnetic fields.

Although magnetoelectric materials have been known for decades, no direct proof of the coupling between the two co-existing physical effects had been reported in the literature. We have demonstrated this magneto-electric coupling by neutron diffraction on BiFeO₃ single crystals. One key to success was the exceptional quality of the high purity single crystals which are magnetically and electrically single domain. More...