ORDERED MAGNETISM IN SOLIDS.
Abstract
Using an automatic recording constant velocity Mossbauer spectrometer, the Mossbauer effect of Fe57 in the 14 rare earth orthoferrites RFeO3 was measured from liquid air temperature to their respective Curie points. It was found that the internal field at O K decreases regularly with the atomic number R from (564 + or - 2) KOe for LaFeO3 to (546 + or - 2)KOe for LuFeO3. The canting angle is essentially constant over the entire temperature region. The sublattice magnetization as a function of temperature was calculated according to Oguchi's spin wave theory together with the exchange integral taken from Rushbrook and Wood. The theoretical result was found to be in good agreement with the internal field as a function of temperature in all the orthoferrites. The internal field as a function of temperature was found to vary as the power 0.38 + or - 0.005 of the temperature, i.e. approximately as the 1/3 power and not as the 1/2 power predicted by the molecular field approximation. The isomer shift was independent of atomic number R at 80 K and was approximately (0.61 + or - 0.03)mm/sec using a source of Co57 in Cr. The quadrupole coupling constant was found to be small with a minimum value of (-0.06 + or - 0.01)mm/sec for SmFeO3 and a maximum of (0.03 + or - 0.01) for GdFeO3. In connection with these Mossbauer studies, a cryofurnace capable of operating from 80 K to 870 K with a temperature stability of better than 1 K was designed and built.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1966
- Accession Number
- AD0810646
Entities
People
- David Treves
- Shmuel Shtrikman
Organizations
- Weizmann Institute of Science