AC conductivity in polycrystalline La1-xCaxMnO3

作者：Shah WH^*; Hasanain SK

来源：Journal of Magnetism and Magnetic Materials, 2002, 246(1-2): 199-206.

DOI：10.1016/S0304-8853(02)00054-9

• conductivity
• polycrystallin
• magnetoresistance

We have studied the DC and AC conductivity in polycrystalline La1-xCaxMnO3 compounds prepared with varying heat treatments. The samples show a marked dependence of resistivity on the heat treatment, and exhibit large magnetoresistance (MR) effects at as well as below T-c. The in-phase part of AC conductivity sigma' was measured in the frequency range f < 100 kHz, and was seen to exhibit a pronounced frequency dependence. There is a low-frequency region of decreasing sigma', followed by a high-frequency region where sigma' increases roughly as f(2). The minimum occurs at a frequency that is temperature dependent. Both the MR below T-c and sigma'(f) dependence are interpreted as being consequences of grain boundary effects in these polycrystalline materials.

• 出版日期2002-4