Magnetic Resonance of Mn2+-Doped LiF Crystals

Abstract

The electron paramagnetic resonance of Mn2+ in powdered LiF was observed at X-band and room temperatures for various impurity concentrations. The highest concentration was examined at K-band and low temperatures to obtain additional information regarding the distribution of Mn2+ ions which were introduced chemically into the lattice in small amounts. In the highest concentration, the K-band spectra indicate that part of the Mn2+ goes into the powder in the form of clusters of Mn and F which are antiferromagnetic at helium temperatures. NMR linewidth measurements on the lithium nuclei at low temperatures are qualitatively explained by the antiferromagnetism. The room-temperature data from the more dilute samples exhibit not only the expected hyperfine splitting but also a superhyperfine splitting. The hyperfine interaction of the Mn2+ ion was determined to be A55=90±2×10—4 cm—1, and the isotropic part of the superhyperfine interaction with each of the six fluorine nearest-neighbor nuclei was measured to be As=17.1±0.5×10—4 cm—1. Comparisons between K-band spectra from chemically prepared powdered samples and single crystals grown from the melt indicate that the melt method is unsuitable for obtaining the solid solution required to examine the superhyperfine spectra.