Pressure dependence of Morin transition in α-Fe2O3 hematite

We report high-pressure neutron diffraction data on the Morin-transition TM in ?-Fe2O3 hematite, up to 8 GPa and under hydrostatic conditions. We find a strictly linear pressure coefficient of with no evidence for intermediate magnetic states as indicated by all previous non-hydrostatic measurements. The behaviour of TM is highly regular and can well be explained within the framework of Artman et al.'s single-ion model if a change of the single-ion anisotropy energy by +1%/GPa is assumed. Such a value seems not to be unusual for iron oxides.