We measure the colossal permittivity in single crystal Fe2TiO5 using broadband spectroscopy in the frequency range 20 Hz - 1 MHz. The relaxation response is analyzed using a Debye-like model with Arrhenius activation in two different ways and yields an energy barrier of 286.1 ± 2.8 meV. DC transport yields an activation energy of 288.8 ± 2.8 meV. These results strongly imply that the energy barrier for localized dipole motion and itinerant charge transport originate from the same atom-level forces. A further implication is that colossal dielectric behavior is a microscopic bulk phenomenon arising from a system on brink of metallicity.
@article{arxiv.2604.22017,
title = {How Electrons Become Mobile in a Colossal Dielectric -- Fe$_2$TiO$_5$},
author = {M. L. McLanahan and A. P. Ramirez},
journal= {arXiv preprint arXiv:2604.22017},
year = {2026}
}