Magnetic collapse and low conductivity of Fe3N in the deep interiors of Earth-like planets

Abstract

The high-pressure behavior of iron nitrides has garnered significant attention due to the possibility of deep nitrogen reservoirs within the Earth’s interior. Here, we investigate the magnetic, structural, electrical, and thermal properties of Fe3N up to 62 GPa and 2100 K, using multiple probes coupled with the diamond-anvil cell technique (including synchrotron X-ray diffraction, synchrotron Mössbauer spectroscopy, and electrical measurements). Fe3N undergoes a magnetic phase transformation from the ferromagnetic to paramagnetic state at ~17-20 GPa, 300 K. The equation of state was determined as, V0/Z = 42.8(1) Å3, and K0 = 151.8(1) GPa, with K′ fixed at 4. Additionally, Fe3N exhibits unexpectedly low electrical and thermal conductivity under high-pressure and high-temperature conditions. This result suggests that deep nitrogen cycling may contribute to the thermal evolution of the deep interiors of Earth and other terrestrial bodies.