Accession Number:

AD0810646

Title:

ORDERED MAGNETISM IN SOLIDS.

Descriptive Note:

Technical rept. 1 Jan 65-31 Mar 66,

Corporate Author:

WEIZMANN INST OF SCIENCE REHOVOT (ISRAEL) DEPT OF ELECTRONICS

Personal Author(s):

• Shtrikman, Shmuel
• Treves, David

Report Date:

1966-12-01

Pagination or Media Count:

107.0

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 - 2KOe 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 Oguchis 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 13 power and not as the 12 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 - 0.03mmsec using a source of Co57 in Cr. The quadrupole coupling constant was found to be small with a minimum value of -0.06 or - 0.01mmsec 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.

Descriptors:

• FERRITES
• LUTETIUM COMPOUNDS
• LANTHANUM COMPOUNDS
• GADOLINIUM COMPOUNDS

Subject Categories:

• Electricity and Magnetism
• Nuclear Physics and Elementary Particle Physics
• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE