Specific features of the magnetic field-induced orientational transition in EuMnO3

It is found that the spin-flop transition in EuMnO₃ manganite induced by a magnetic field H parallel to the b axis is accompanied not only by a magnetization jump and magnetostriction anomalies but also by the appearance of electric polarization in the vicinity of the transition field H_cr ～ 200 kOe. This phenomenon can be associated with the occurrence of magnetically inhomogeneous (modulated) states in the vicinity of H_cr. In these states, the system loses the center of symmetry, which allows for the appearance of the polarization. The formation of such states in a magnetic field is caused by the general tendency of the occurrence of magnetically inhomogeneous (incommensurate) structures in the RMnO₃ series due to the frustration of exchange interactions with decreasing ionic radius of the rare-earth ion R starting with R = Eu.