Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

TL;DR

This study reveals a pressure-induced electronic topological transition in hcp iron driven by electron correlation effects, evidenced by experimental anomalies and first-principles simulations, highlighting the importance of many-electron interactions.

Contribution

The paper demonstrates that correlation effects induce an electronic topological transition in hcp iron, which is absent in one-electron models, emphasizing the role of many-electron physics.

Findings

Transition occurs at ~40 GPa pressure.

Anomalous behavior in sound velocity, lattice ratio, and Mössbauer shift.

Transition driven by many-electron effects, not captured by one-electron calculations.

Abstract

We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio and M\"ossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe.