Antiferromagnetism in hcp Iron-Ruthenium and hcp Iron-Osmium Alloys

Abstract

The magnetic properties of Fe-Ru and Fe-Os alloys in hcp Fe-rich regions were studied in connection with magnetism of hcp Fe and antiferromagnetism was found at low temperatures by means of Mössbauer effect and thermoelectric power measurements. The Néel temperature and the internal magnetic field of hcp Fe obtained by extrapolation are 100°K and 16 kG, respectively. Magnetic moment of hcp Fe was estimated from the internal magnetic field to be about 0.1 µ _B consistent with the results of neutron diffraction measurements. The quadrupole splittings and the isomer shifts relative to bcc Fe of the alloys are extrapolated to 0.14 mm/sec and -0.21 mm/sec, respectively, at pure hcp Fe. In Fe-Ru alloys, gradients of the thermoelectric power versus temperature curves in high temperature region change sign as expected from the density of state of the alloys. On the other hand, the increase in the magnetic susceptibilities with approaching to pure hcp Fe is unexplainable simply by the composition dependence of the density of states.