Epsilon-iron as a spin-smectic state
Abstract
Using x-ray emission spectroscopy, we find appreciable local magnetic moments until 30-40 GPa in the high-pressure phase of iron, however no magnetic order is detected with neutron powder diffraction down to 1.8 K contrary to previous predictions. Our first-principles calculations reveal a "spin-smectic" state lower in energy than previous results. This state forms antiferromagnetic bilayers separated by null spin bilayers, which allows a complete relaxation of the inherent frustration of antiferromagnetism on a hexagonal close-packed lattice. The magnetic bilayers are likely orientationally disordered, owing to the soft interlayer excitations and the near-degeneracy with other smectic phases. This possible lack of long-range correlation agrees with the null results from neutron powder diffraction. An orientationally-disordered, spin-smectic state resolves previously perceived contradictions in high pressure iron and could be integral to explaining its puzzling superconductivity.
Cite
@article{arxiv.1903.04792,
title = {Epsilon-iron as a spin-smectic state},
author = {Blair W. Lebert and Tommaso Gorni and Michele Casula and Stefan Klotz and François Baudelet and James M. Ablett and Thomas C. Hansen and Amélie Juhin and Alain Polian and Pascal Munsch and Gilles Le Marchand and Zailan Zhang and Jean-Pascal Rueff and Matteo d'Astuto},
journal= {arXiv preprint arXiv:1903.04792},
year = {2019}
}