Accession Number : AD0764635

Title :   Mossbauer Study of Magnetic States of KFeF3 and Implications for RbFeF3.

Descriptive Note : Technical rept.,

Corporate Author : PENNSYLVANIA UNIV PHILADELPHIA DEPT OF PHYSICS

Personal Author(s) : Davidson,Gerald R. ; Eibschutz,M. ; Guggenheim,H. J.

Report Date : JUL 1973

Pagination or Media Count : 70

Abstract : Mossbauer absorption spectra of 57Fe in an unstrained (100) single crystal platelet of KFeF3 have been measured between 297 and 4.2K. The transition to the trigonal antiferromagnetic state occurred at T9N) = 112.5 plus or minus 0.5K. Analysis of the data in the antiferromagnetic phase indicates the spin alignment is parallel to the <111> distortion. The temperature dependence of H(hf) and delta E(Q) in this phase is compared with predictions of self-consistent molecular field theory calculations. Only fair agreement is found with the magnetically induced EFG model, which describes the Fe(2+) ion by a Hamiltonian incorporating free ion terms, a cubic crystal field, and an exchange interaction. A substantially better fit is obtained with a second model. Application of this second model to the tetragonal antiferromagnetic state of RbFeF3 indicates the spins align parallel to a <100> direction rather than the <111> direction predicted previously by use of the magnetically induced EFG model. (Modified author abstract)

Descriptors :   (*IRON COMPOUNDS, *ANTIFERROMAGNETISM), NUCLEAR RADIATION SPECTROSCOPY, MOSSBAUER EFFECT, FLUORIDES, POTASSIUM COMPOUNDS, RUBIDIUM COMPOUNDS, SINGLE CRYSTALS, ELECTRIC FIELDS, LINE SPECTRA, ABSORPTION SPECTRA

Subject Categories : Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE