| Автор | U J Cox |
| Автор | L D Cussen |
| Дата выпуска | 1989-06-12 |
| dc.description | For pt.I see ibid., vol.1, p.3565 (1989). The frequency dependence of the critical fluctuations at the antiferrodistortive phase transition exhibited by the disordered crystals KMn<sub>0.99</sub>Mg<sub>0.01</sub>F<sub>3</sub> and KMn<sub>0.9</sub>Mg<sub>0.1</sub>F<sub>3</sub> has been studied using neutron scattering techniques. In pure KMnF<sub>3</sub> the soft R<sub>25</sub> mode is overdamped for temperatures below approximately (T<sub>c</sub>+40) K. A similar behaviour is observed in the disordered crystals, but the damping constant is increased by the presence of the impurities. The amplitude of the central peak observed in the spectral response of pure KMnF<sub>3</sub> is not significantly increased by the addition of the impurities. This is consistent with measurements of the anomalous component observed close to T<sub>c</sub> in complimentary X-ray scattering studies, which showed that this component was reduced by the addition of impurities. The results further indicate that although the temperature dependence of the anomalous scattering is similar in both the X-ray and neutron scattering experiments, the neutron central peak persists over the temperature range T<sub>c</sub> to (T<sub>c</sub>+20) K while the X-ray anomaly was only observed for a few degrees above T<sub>c</sub>. Thus, while the anomalous scattering measured using the two techniques is related to the impurity concentration in the disordered crystals, the two features must be to some extent distinct. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | The effect of impurities on the R-point instability in KMnF<sub>3</sub>. II. A neutron scattering study |
| Тип | paper |
| DOI | 10.1088/0953-8984/1/23/003 |
| Electronic ISSN | 1361-648X |
| Print ISSN | 0953-8984 |
| Журнал | Journal of Physics: Condensed Matter |
| Том | 1 |
| Первая страница | 3579 |
| Последняя страница | 3589 |
| Аффилиация | U J Cox; Dept. of Phys., Edinburgh Univ., UK |
| Аффилиация | L D Cussen; Dept. of Phys., Edinburgh Univ., UK |
| Выпуск | 23 |
