Ferroelectric phase transition induced by charge transfer vibronic excitons in ferroelectric oxides

It is shown theoretically that bi-polaronic excitons (charge transfer vibronic excitons – CTVE) in ferroelectric oxides can induce a significant positive shift of the ferroelectric phase transition temperature under strong enough optical or X-ray pumping (producing CTVEs in ∼10¹⁶ cm^–3 concentration range). Incipient ferroelectrics KTaO₃ and SrTiO₃ could serve as a good example. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)