Dielectric spectroscopy and lattice dynamics of magnetoelectric multiferroics and strained ferroelectric thin films (Magnetoelektrika)

Lattice dynamics, dielectric and magnetic properties of various magnetoelectric multiferroic strained thin films will be compared with properties of the bulk samples. Dielectric properties will be investigated from 100 Hz to 150 THz with the emphasis on microwave, THz and infrared region, because the defect-induced localized conductivity does prevent the study of the intrinsic dielectric response at low frequencies. We intend to investigate not only ferroelectric soft modes driving the ferroelectric phase transitions, but also electromagnons. In the case of quantum paraelectric EuTiO3 we will investigate tuning of the soft mode frequency with the magnetic field and its dependence on the strain. In the case of FeTiO3 we will investigate theoretically predicted new weak-ferromagnetism induced by the ferroelectric order. BiFeO3/BiCrO3 heterostructures will be compared with BiFeO3 thin films. Bulk properties of BiMnO3 will be compared with the thin films. Effect of the strain on the ferroelectric transition in the quantum paraelectric SrTiO3 and Srn+1TinO3n+1 will be investigated, too.