Dynamics of the Magnetic and Structuralα−εPhase Transition in Iron

Abstract

We have studied the high-pressure iron bcc to hcp phase transition by simultaneous x-ray magnetic circular dichroism and x-ray absorption spectroscopy with an x-ray energy dispersive spectrometer. The combination of the two techniques allows us to obtain simultaneously information on both the structure and the magnetic state of iron under pressure. The magnetic and structural transitions simultaneously observed are sharp. Both are of first order in agreement with the theoretical prediction. The pressure domain of the transition observed (2.4+/-0.2 GPa) is narrower than that usually cited in the literature (8 GPa). Our data indicate that the magnetic transition slightly precedes the structural one, suggesting that the origin of the instability of the bcc phase in iron with increasing pressure is to be attributed to the effect of pressure on magnetism as predicted by spin-polarized full-potential total energy calculations.

The Time-resolved and Extreme-conditions XAS (TEXAS) facility at the European Synchrotron Radiation Facility: the energy-dispersive X-ray absorption spectroscopy beamline ID24

“…Because pressure acts directly on interatomic distances, band hybridization strength can be tuned which may induce magnetic instabilities leading to structural phase transitions, to non-ferromagnetic phases or to partial suppression of magnetic moments or ferromagnetic order. K-edge X-ray magnetic circular dichroism (XMCD) is a powerful probe to investigate the effect of pressure on structure and magnetism in 3d metals and their compounds (Mathon et al, 2004;Torchio et al, 2014b). Along with temperature and pressure, high magnetic fields can also tune matter through various structural and magnetic phases featuring novel and exotic properties.…”

Local structure and spin transition inFe2O3hematite at high pressure

“…1) and of the electronic transition (Fig. 3) is fundamental to overcome the uncertainty due to different hydrostatic conditions and different measured volume, and allows addressing questions related to the interplay between structural and electronic/magnetic degrees of freedom in Fe 2 O 3 , as previously demonstrated for pure Fe [33]. In Fig.…”

Probing the extended non-Fermi liquid regimes of MnSi and Fe

“…Elemental iron displays, in its non-magnetic ǫ−phase, non-Fermi liquid behavior with striking characteristics. [2] The NFL region emerges close to a strong first order magnetic transition, followed by a structural one, [3] and extends between pc1 ≈ 13 GPa and almost 2pc1. [2] Furthermore, in this pressure window Fe is an unconventional superconductor (SC) * Corresponding author.…”