| Автор | A I Coldea |
| Автор | L E Spring |
| Автор | S J Blundell |
| Автор | J Singleton |
| Автор | W Hayes |
| Дата выпуска | 1999-11-22 |
| dc.description | We study effects on magnetotransport produced by changing the size of the trivalent ions R<sup>3+</sup> in the layered polycrystalline materials Sr<sub>2</sub>RMn<sub>2</sub>O<sub>7</sub> (R = Pr,Nd,Ho,Y) and by varying the mixed-valence ratio Mn<sup>3+</sup>/Mn<sup>4+</sup> in the series Sr<sub>2-x</sub>Nd<sub>1+x</sub>Mn<sub>2</sub>O<sub>7</sub> (x = 0,0.1,0.2,0.5). The results of our magnetic and electrical measurements are related to the measured structural characteristics of each compound. For the Sr<sub>2</sub>RMn<sub>2</sub>O<sub>7</sub> series, colossal magnetoresistance (CMR) is observed below 150 K for R = Pr and R = Nd but not for samples containing R = Ho or R = Y ions, which have smaller ionic radii. For R = Ho and R = Y, the absence of CMR is correlated with the paramagnetic and insulating properties of the samples. Within the series Sr<sub>2-x</sub>Nd<sub>1+x</sub>Mn<sub>2</sub>O<sub>7</sub>, the CMR effect is also observed for temperatures below 150 K and increases as the temperature decreases. In this series the samples show a mixture of spin-glass and antiferromagnetic behaviour (x = 0,0.1) or no long-range magnetic order (x = 0.2,0.5). The largest CMR at high temperatures (above 100 K) and high magnetic fields (14 T) is observed for the x = 0.2 sample, which also shows the largest magnetization per formula unit. The observed CMR in the compounds studied here is attributed to magnetic cluster formation. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | Magnetotransport studies on the Ruddlesden Popper phases Sr<sub>2</sub>RMn<sub>2</sub>O<sub>7</sub> (R = Nd, Pr, Ho, Y) and Sr<sub>2-x</sub>Nd<sub>1+x</sub>Mn<sub>2</sub>O<sub>7</sub> (x = 0, 0.1, 0.2, 0.5) |
| Тип | paper |
| DOI | 10.1088/0953-8984/11/46/308 |
| Electronic ISSN | 1361-648X |
| Print ISSN | 0953-8984 |
| Журнал | Journal of Physics: Condensed Matter |
| Том | 11 |
| Первая страница | 9053 |
| Последняя страница | 9072 |
| Аффилиация | A I Coldea; Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK |
| Аффилиация | L E Spring; Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK |
| Аффилиация | S J Blundell; Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK |
| Аффилиация | J Singleton; Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK |
| Аффилиация | W Hayes; Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK |
| Выпуск | 46 |
