Pressure and magnetic field dependence of the low temperature resistivity of PF6-doped polypyrrole
| Autor: | Daniel Moses, M. Reghu, C.O. Yoon, A. J. Heeger |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Condensed matter physics
Mechanical Engineering Doping Metals and Alloys Conductivity Condensed Matter Physics Polypyrrole Electronic Optical and Magnetic Materials Magnetic field Metal chemistry.chemical_compound chemistry Mechanics of Materials Electrical resistivity and conductivity visual_art Materials Chemistry visual_art.visual_art_medium Temperature coefficient Ambient pressure |
| Zdroj: | Synthetic Metals. 64:53-57 |
| ISSN: | 0379-6779 |
| DOI: | 10.1016/0379-6779(94)90274-7 |
| Popis: | The temperature coefficient of the resistivity (TCR) of doped polypyrrole changes sign below 25 K, from negative to positive, in samples with relatively weak disorder (as inferred from the resistivity ratio, ϱ r = ϱ (1.4 K)/ ϱ (300 K)). We have studied the crossover from negative to positive TCR as a function of the disorder, and as a function of pressure and magnetic field. At ambient pressure, the sign change is systematically observed only for samples having ϱ r ⩽2. For example, when ϱ r decreases from 1.97 to 1.33, the temperature ( T 1 ) defining the transition from negative to positive TCR increases from 7.5 to 24 K. Pressure enhances interchain transport and thereby decreases ϱ r . For samples having ϱ r ≈ 2–10, the TCR transition can be induced by applying high pressure. A magnetic field of 8 T suppresses the TCR transition. This anomalous temperature dependence of the low temperature electrical transport is discussed in terms of correlation corrections to the conductivity in the disordered metallic regime near the metal-insulator transition. |
| Databáze: | OpenAIRE |
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