The ferromagnetic interstitial iron compound ${\mathrm{F}\mathrm{e}}_3\mathrm{C}$ (cementite) is expected to have Invar properties, whereby a high-moment to low-moment transition should occur when the atomic volume is reduced below a critical value. We, therefore, examine the pressure dependence of the Fe $K$-edge x-ray magnetic circular dichroism in ${\mathrm{F}\mathrm{e}}_3\mathrm{C}$ at ambient temperature and pressures up to 20 GPa. We find clear evidence for a high-moment to low-moment transition around 10 GPa.

• Received 1 October 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.075502