Mechanical properties of multiferroic Bi2Mn4O10: Full set of elastic constants determined by inelastic neutron scattering

The full matrix of elastic constants of multiferroic Bi2Mn4O10 has been determined at ambient conditions using phonon spectroscopy. The dispersion of acoustic phonons in a single crystal was measured at the three axes neutron spectrometer PUMA@FRM II for different propagation directions. The magnitudes of the independent nine elastic constants show that the mechanical behavior is strongly anisotropic with a soft direction which almost coincides with the magnetization vector in the low-temperature multiferroic phase. The anisotropy can be related to the different types of links between the building blocks of the mullite structure. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim