## SCL Seminar by Jernej Mravlje

SCL seminar of the Center for the Study of Complex Systems, will be held on Monday, 26 December 2016 at 14:00 in the library reading room “Dr. Dragan Popović" of the Institute of Physics Belgrade. The talk entitled

will be given by Dr. Jernej Mravlje ("Jozef Stefan" Institute, Ljubljana, Slovenia).

The Earth's magnetic field is essential for the life as it protects the ozone layer from the solar wind. The magnetic field exists due to the geodynamo mechanism which is driven by convective processes in the liquid iron external core. Sufficiently low thermal conductivity is essential for the existence of the convection. Recently it has been discovered that the electron-phonon interaction is less efficient than believed earlier [1] and that the thermal conductivity is about 5 times larger than assumed in geophysical models, which questions what ensures the stability of the geodynamo. Work [2] suggested electron-electron interactions could play an important role. It considered hcp-Fe, believed to be the main constituent of the Earth's inner core, under 300 GPa and 6000K present there and found a non-Fermi liquid behavior and large resistivity of the same magnitude as the electron-phonon one. We repeated the same calculations more precisely [3] and found that the hcp-Fe behaves as a Fermi liquid and that the calculated resistivity is about 1/4th of the one found due to the electron-electron scattering due to numerical mistakes in [2], which led to retraction of the paper. We calculated also thermal conductivity. The effect of electron-electron scattering on thermal conductivity is due to a breakdown of Wiedemann-Franz law larger than the effect on electrical conductivity. The calculated thermal conductivity is 540W/mK which is similar to the one obtained from the electron-electron scattering 300W/mK [4], which suggests electron-electron scattering plays a non-negligible role in the dynamics of the Earth's core.

[1] M. Pozzo, C. Davies, D. Gubbins, and D. Alfe, Nature 485, 355,(2012).

[2] P. Zhang, R.E. Cohen, and K. Haule, Nature 517, 605 (2015).

[3] L. V. Pourovskii, J. Mravlje, A. Georges, S.I. Simak, I. A. Abrikosov, arXiv:1603.02287 (2016)

[4] M. Pozzo, C. Davies, D. Gubbins, and D. Alfe, Earth and Planet. Sci. Lett. 393, 159 (2014).

**"Correlated-electron transport in hcp-Fe under extreme conditions present in inner Earth Core"**will be given by Dr. Jernej Mravlje ("Jozef Stefan" Institute, Ljubljana, Slovenia).

**Abstract of the talk:**The Earth's magnetic field is essential for the life as it protects the ozone layer from the solar wind. The magnetic field exists due to the geodynamo mechanism which is driven by convective processes in the liquid iron external core. Sufficiently low thermal conductivity is essential for the existence of the convection. Recently it has been discovered that the electron-phonon interaction is less efficient than believed earlier [1] and that the thermal conductivity is about 5 times larger than assumed in geophysical models, which questions what ensures the stability of the geodynamo. Work [2] suggested electron-electron interactions could play an important role. It considered hcp-Fe, believed to be the main constituent of the Earth's inner core, under 300 GPa and 6000K present there and found a non-Fermi liquid behavior and large resistivity of the same magnitude as the electron-phonon one. We repeated the same calculations more precisely [3] and found that the hcp-Fe behaves as a Fermi liquid and that the calculated resistivity is about 1/4th of the one found due to the electron-electron scattering due to numerical mistakes in [2], which led to retraction of the paper. We calculated also thermal conductivity. The effect of electron-electron scattering on thermal conductivity is due to a breakdown of Wiedemann-Franz law larger than the effect on electrical conductivity. The calculated thermal conductivity is 540W/mK which is similar to the one obtained from the electron-electron scattering 300W/mK [4], which suggests electron-electron scattering plays a non-negligible role in the dynamics of the Earth's core.

[1] M. Pozzo, C. Davies, D. Gubbins, and D. Alfe, Nature 485, 355,(2012).

[2] P. Zhang, R.E. Cohen, and K. Haule, Nature 517, 605 (2015).

[3] L. V. Pourovskii, J. Mravlje, A. Georges, S.I. Simak, I. A. Abrikosov, arXiv:1603.02287 (2016)

[4] M. Pozzo, C. Davies, D. Gubbins, and D. Alfe, Earth and Planet. Sci. Lett. 393, 159 (2014).