The magnetic mystery at the center of the Earth

At the temperatures reached during earlier lab experiments, Cohen’s simulation agreed with the previous higher predictions of iron’s conductivity. Above around 1,700°, however, an overlooked interaction took center stage. In addition to electrons scattering off of vibrating iron atoms, the thermally energized electrons crossed paths more often and started colliding with each other. At core conditions, this electron-electron scattering became just as important as the electron-iron scattering. This addition essentially doubled the resistivity, which cut the thermal conductivity to about 105 W/(m•K), roughly half the 2012 estimates, the researchers reported in the January 29 Nature.