Magnetic instabilities in Fe3C cementite particles observed with Fe K-edge x-ray circular dichroism under pressure.

ABSTRACT

The ferromagnetic interstitial iron compound Fe(3)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 Fe(3)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.