Abstract
Comparison of the DC resistivity, magnetisation, 55 Mn NMR, AC susceptibility and microwave impedance of single crystalline and bulk polycrystalline samples of La0.9Ca0.1MnO3 reveals the complexity of these materials. The observation of a motionally narrowed peak in the NMR data is indicative of double exchange ferromagnetism existing in isolated metallic regions, whilst combined magnetisation and DC resistivity suggest that at macroscopic scales the material is a super-exchange mediated ferromagnetic insulator. High-frequency conductivity measurements are used to search for evidence of non-percolative metallic clusters. The microwave signature associated with the metal insulator transition in micron sized isolated particulates of La0.67Ca0.33MnO3 were studied in order to establish how metallic cluster formation might be identified. (C) 2002 Elsevier Science B.V. All rights reserved.
| Original language | English |
|---|---|
| Pages (from-to) | 105-114 |
| Number of pages | 10 |
| Journal | Journal of Magnetism and Magnetic Materials |
| Volume | 260 |
| Publication status | Published - Mar 2003 |
Keywords
- manganites
- low doping
- phase separation
- NUCLEAR-MAGNETIC-RESONANCE
- PHASE-SEPARATION
- MAGNETORESISTANCE MANGANITES
- ANTIFERROMAGNETIC-RESONANCE
- GIANT MAGNETORESISTANCE
- NEUTRON-SCATTERING
- SURFACE-RESISTANCE
- LA1-XCAXMNO3
- LA1-XSRXMNO3
- RESISTIVITY