Lattice-strain versus dynamic effects in electron spin resonance studies of Rb<sub>1-x</sub>(NH<sub>4</sub>)<sub>x</sub>H<sub>2</sub>PO<sub>4</sub>
P K Kahol; X Lao; M B Costello; N S Dalal; P K Kahol; Dept. of Phys., Wichita State Univ., KS, USA; X Lao; Dept. of Phys., Wichita State Univ., KS, USA; M B Costello; Dept. of Phys., Wichita State Univ., KS, USA; N S Dalal; Dept. of Phys., Wichita State Univ., KS, USA
Журнал:
Journal of Physics: Condensed Matter
Дата:
1994-04-11
Аннотация:
A methodology for investigating dynamics of various spin probes in mixed/glassy systems of the KH<sub>2</sub>PO<sub>4</sub> type is developed. Using this methodology, electron spin resonance (ESR) features of the AsO<sub>4</sub><sup>4-</sup> centre in the paraelectric phase of Rb<sub>1-x</sub>(NH<sub>4</sub>)<sub>x</sub>H<sub>2</sub>PO<sub>4</sub> are shown to arise from strain-broadening and motional-broadening effects. These conclusions are in disagreement with those of a recent study, which implicated the various features observed in the existence of ferroelectric-antiferroelectric fluctuations in Rb<sub>1-x</sub>(NH<sub>4</sub>)<sub>x</sub>H<sub>2</sub>PO<sub>4</sub>. It is additionally shown that hyperfine couplings from Rb isotopes make the dominant contribution to the ESR spectra in Rb-containing compounds.
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