EuTiO3 is an incipient ferroelectric antiferromagnet attracting attention of multiferroic community for several reasons. First, due to its unusually strong non-linear, third order (E2H2-type) magnetoelectric coupling, which is demonstrated via a magnetodielectric (spin-phonon coupling) effect below Néel temperature of about 5 K. Second, because of the possible induction of ferroelectricity at low temperatures bybiaxial strain or barium doping. Thus, induced multiferroic system could exhibit interesting magnetoelectric coupling. Moreover, its affinity with SrTiO3 and BaTiO3 predetermine these compounds to form (Eu, Ba, Sr)TiO3 solid-state solution with remarkable properties. One of them ispossible existence of multiferroic quantum criticalities causing an unconventional temperature dependence of low-temperature electric and magnetic susceptibility.
Apart from the overview of basic properties of EuTiO3, the lecture is focused on theseemingly anisotropic behaviour of the magnetodielectric effect, observation of the ferromagnetic resonance shift from microwave to THz region with external magnetic field, and discussion of preliminary results concerning the multiferroic quantum critical behaviour in (Eu, Ba, Sr)TiO3 solid solutions.
 D. Repček, et. al., Physical Review B 102, 144402 (2020).
 A. Narayan, A. Cano, A. V. Balatsky, and N. A. Spaldin, Nature Materials 18, 223 (2019).