Pressure dependence of the Verwey transition in magnetite: an infrared   spectroscopic point of view
  We investigated the electronic and vibrational properties of magnetite at temperatures from 300 K down to 10 K and for pressures up to 10 GPa by far-infrared reflectivity measurements. The Verwey transition is manifested by a drastic decrease of the overall reflectance and the splitting of the phonon modes as well as the activation of additional phonon modes. In the whole studied pressure range the down-shift of the overall reflectance spectrum saturates and the maximum number of phonon modes is reached at a critical temperature, which sets a lower bound for the Verwey transition temperature T$_{\mathrm{v}}$. Based on these optical results a pressure-temperature phase diagram for magnetite is proposed. 
J. Ebad-Allah, L. Baldassarre, M. Sing, R. Claessen, V. A. M. Brabers,   and C. A. Kuntscher
cond-mat.str-el