Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 5: Cooperative Phenomena and Phase Transitions (joint session MA/TT)

MA 5.12: Talk

Monday, March 16, 2020, 12:15–12:30, HSZ 401

Epsilon iron as a spin-smectic state — Tommaso Gorni¹ and •Michele Casula² — ¹Laboratoire de Physique et d’Étude des Matériaux, École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, Université Paris Sciences et Lettres, 75005 Paris, France — ²Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, 4 Place Jussieu, 75005 Paris, France

By first-principles and spin-model calculations, we study the high-pressure epsilon phase of iron. We reveal the existence of a modulated spin pattern, lower in energy than the previous results, where spin fluctuations lead to the formation of antiferromagnetic bilayers separated by null spin bilayers. This pattern is analogous to the smectic phase found in liquid crystals. 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 neutron powder diffraction and could be integral to explaining its puzzling superconductivity.