Iron spin crossover in ferropericlase and its effect on lower-mantle thermal conductivity

Alexander F. Goncharov; Irina Chuvashova; Eric Edmund; JungFu Lin; Zena Younes; Nicolas Jaisle; Axel Phelipeau; Carmen Sanchez-Valle; Christoph Otzen; Clemens Prescher; Hanns-Peter Liermann; Nico Giordano; James McHardy; Karen Appel; Michal Andrzejewski; S. V. Rahul; Minxue Tang; Jolanta Sztuk-Dambietz; Thomas Michelat; Torsten Laurus; Malcolm McMahon; Mark Robertson; Rachel Husband; Efim Kolesnikov; Sebastien Merkel; Silvia Boccato; Carsten Baehtz; Guillaume Morard; Emma S. Bullock; Cornelius Strohm; Zuzana Konopkova; Ryan Stewart McWilliams

arXiv · 2604.14183

Iron spin crossover in ferropericlase and its effect on lower-mantle thermal conductivity

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Abstract

Thermal conductivity of Earths lower mantle controls heat transfer across the core-mantle boundary (CMB) and strongly influences mantle convection. We report direct measurements of the thermal conductivity of single-crystal ferropericlase (Mg$_{1-x}$Fe$_x$O, $x = 0.09$-0.13), the second most abundant lower-mantle mineral, using optical laser flash and X-ray free-electron laser heating in diamond-anvil cells up to $\sim2200$~K and 130~GPa. These experiments provide the first conductivity data for ferropericlase at simultaneous lower-mantle pressures and temperatures. A marked reduction in conductivity between 60 and 100~GPa at $\sim1700$~K is consistent with the iron spin crossover. Combined with our previous results for Fe- and Fe,Al-bearing bridgmanite, the data define a lower-mantle conductivity profile that increases with pressure to $\sim10$~W\,m$^{-1}$\,K$^{-1}$ near the CMB, constraining mantle heat flux, plume buoyancy, and long-term geodynamic evolution.

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Alexander F. Goncharov, Irina Chuvashova, Eric Edmund, JungFu Lin, Zena Younes, Nicolas Jaisle, Axel Phelipeau, Carmen Sanchez-Valle, Christoph Otzen, Clemens Prescher, Hanns-Peter Liermann, Nico Giordano, James McHardy, Karen Appel, Michal Andrzejewski, S. V. Rahul, Minxue Tang, Jolanta Sztuk-Dambietz, Thomas Michelat, Torsten Laurus, Malcolm McMahon, Mark Robertson, Rachel Husband, Efim Kolesnikov, Sebastien Merkel, Silvia Boccato, Carsten Baehtz, Guillaume Morard, Emma S. Bullock, Cornelius Strohm, Zuzana Konopkova, Ryan Stewart McWilliams. 2026-03-31. Iron spin crossover in ferropericlase and its effect on lower-mantle thermal conductivity. https://arxiv.org/abs/2604.14183

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