Evidence for the magnetoelectric effect in nickel-bromine boracite, Ni3B7O13 Br

摘要: Abstract A ferromagnetic/ferroelectric/ferroelastic phase, consistent with point group m'm2’ and Tc(f. m.)= 17K, has been identified by measurements of the magnetoelectric coefficient α32, peak value at Tc(7 ps/m), ferromagnetic coercive field, Hc, versus temperature. effect persists above 17K up to ∼ 30K indicating a phase still unknown nature. The dielectric constant e33 is insensitive magnetic ordering, but striking anomaly spontaneous polarization, →Ps, occurs in ordering range attributed interaction. Furthermore, →Ps its maximum (290 nC/cm2) TC(f. e)