Thermal conductivity of dense hcp iron: Direct measurements using laser heated diamond anvil cell

Thermal conductivity (k) of iron is measured up to about 134 GPa. The measurements are carried out using the single sided laser heated diamond anvil cell, where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical method. Thermal conductivity of fcc (gamma) - Fe increases up to a pressure of about 46 GPa. We find thermal conductivity values in the range of 70-80 Wm(-1)K(-1) (with an uncertainty of 40%), almost constant with pressure, in the hcp (epsilon) phase of Fe. We attribute the pressure independent k above 46 GPa to the strong electronic correlation effects driven by the electronic topological transition (ETT). We predict a value of thermal conductivity of epsilon -Fe of about 40 +/- 16 Wm(-1)K(-1) at the outer core of Earth.