Electronic correlations and transport in iron at Earth’s core conditions

The transport properties of iron under Earth’s inner core conditions are essential input for the geophysical modelling but are poorly constrained experimentally. Here we show that the thermal and electrical conductivity of iron at those conditions remains high even if the electron-electron-scattering (EES) is properly taken into account. This result is obtained by ab initio simulations taking into account consistently both thermal disorder and electronic correlations. Thermal disorder suppresses the non-Fermi-liquid behaviour of the body-centred cubic (bcc) iron phase, hence, reducing the EES; the total calculated thermal conductivity of this phase is 220 Wm^-1K^-1 with the EES reduction not exceeding 20%. The EES and electron-lattice scattering are intertwined and cannot be treated separately. The total conductivity thus exhibits a markedly weaker dependence on the EES as compared with predictions of the Matthiessen’s rule. In the hexagonal close-packed iron the EES is also not increased by thermal disorder and remains weak; the calculated total thermal conductivity, 214 Wm^-1K^-1, is very close to that in bcc-Fe. Our main finding thus holds for the both likely iron phases in the inner core.

L. V. Pourovskii, J. Mravlje, M. Pozzo and D. Alfè, Nat. Comm. 11, 4105 (2020).