Theoretical Investigations of the Sideband Effect in Mössbauer Spectra of FeBO₃

Abstract

A theoretical investigation of the sideband effect in Mossbauer spectra of FeBO, induced by radio frequency (rf) magnetic fields is presented. Because the interpretation of the sideband effect of FeBO, with existing theoretical models reveals no satisfactory results modifications are developed to improve the description. Especially nonlinear acoustic properties of the sample under investigation are taken into account. It can be shown that new resonances occur leading to additional sidebands at fractional integers of the applied rf frequency which have also been experimentally observed. Taking into account this feature an improved empirical description of the sideband effect of FeBO, is developed. This implies that nonlinear acoustic properties must be considered to obtain an appropriate description of the sideband generation in FeBO,.

The effect of a radio-frequency magnetic field on resonant absorption saturation in FeBO3

“…Nevertheless even at the 10 MHz RF field used the very complicated spectra with the overlapping sidebands of many orders and polarization properties were observed. Consequently it was found that the most suitable frequency of RF field is of the order of few MHz (4 MHz), when the sidebands overlapping is minimal and the sidebands of higher order are generated even at very low RF field intensity (<3 Oe) allowing to work in the linear part of field dependence of the FeBO 3 second-order elastic constant C 44 [22].…”

“…The generation of RF sidebands in FeBO 3 was studied thoroughly in Refs. [20][21][22]. It was revealed that in FeBO 3 crystal numerous RF sidebands of higher order appear even at low field intensities only of few decimal fraction of Oe.…”

“…It was revealed that in FeBO 3 crystal numerous RF sidebands of higher order appear even at low field intensities only of few decimal fraction of Oe. The increase of the RF field intensity causes the narrowing of Zeeman pattern, the increase of sidebands of higher order and finally leads to collapse of hyperfine pattern to the central line accompanied by sidebands when the RF field frequency is larger than the Larmor frequency (∼25 MHz) [20][21][22]. The resulting spectra are very complicated because of the simultaneous effect of the collapse and sidebands phenomena.…”