Neutron Scattering Measurements on bulk BiFeO$_{\mathrm{\mathbf{3}}}

Of a long list of multiferroic materials, BiFeO$_{\mathrm{3}}$ is arguably one of the most interesting multiferroic materials as it displays rare room-temperature multiferroic behavior: T$_{\mathrm{N}}=$650 K and T$_{\mathrm{C}}=$1050 K. Hence BiFeO$_{\mathrm{3}}$ has been extensively investigated for potential applications. It also has a very interesting incommensurate magnetic phase transition with an extremely long period of 650 {\AA}. In this talk, I will present our latest results [1-4] mainly obtained from high-resolution neutron scattering experiments on this fascinating material. Using the vast amount of the data, I will sketch a coherent picture of the rare room-temperature multiferroic behavior and, most importantly, a full spin Hamiltonian of BiFeO$_{\mathrm{3}}$.\\ \\$[1]$ Jaehong Jeong, et al., Phys. Rev. Lett. 108, 077202 (2012)\newline [2] Sanghyun Lee et al., Phys. Rev. B Rapid Comm. 88, 060103R (2013)\newline [3] Jaehong Jeong, et al., Phys. Rev. Lett. 113, 107202 (2014)\newline [4] [Review] Je-Geun Park, et al., J. Phys.: Condens. Matter 26, 433202 (2014)