Аннотация:Strontium titanate SrTiO3 is a canonical example of a quantum paraelectric. Its doping with manganese ions unlocks its potential as a quantum multiferroic candidate. However, up to now, the specifi cs of incorporation of the manganese ions into the perovskite ABO3 -type lattice of SrTiO3 and its impact on structure−property elationships are debatable. We prepare Mn-doped SrTiO3 single crystals, SrTi1-xMnxO3 (x=2 at. %), and study it with terahertz (THz) and radio-frequency (RF) spectroscopy. We clearly observe THz ferroelectric soft mode, whose dielectric strength Δε grows while cooling and coincides with the lower-frequency RF permittivity, and whose frequency behavior follows the Cochran law [1]. Qualitative and even quantitative similarities of the temperature-dependentsoft mode parameters in SrTi1-xMnxO3 with those in pure SrTiO3 indicates no strong eff ect of Mn doping on the suppression of the ferroelectric instability. At the same time, using high-precision X-ray diff raction, we discover clear fi ngerprints of the displacement disorder of Mn cations in the perovskite B-sublattice. Moreover, near the temperature of the antiferrodistortive phase transition (105-110 K), the off -center Mn position is shown to split in two, providing the unequal potential barriers distribution for possible local atomic hopping. We believe that such hopping is responsible for the two Arrhenius-type relaxation processes we observe below 1 MHz. The processes have similar activation energies (35 and 43 meV) and attempt frequencies (1 × 1011 and ∼1.6 × 1010 Hz), suggesting similar relaxation mechanisms. Such mechanism has been reliably confi rmed for A-substituted Sr1-xMnxTiO3 [2] but was overlooked in B-substituted samples. To the best of our knowledge, this is the fi rst time that an off -center position of Mn in B-substituted SrTiO3 has been observed, which expands our understanding of the dielectric and possible multiferroic properties of quantum materials.
