Possible influence of the Fermi level position inside the conduction band of high-Tc oxides on the temperature dependence of their resistivity
✍ Scribed by V.R Valiakhmetov
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 691 KB
- Volume
- 227
- Category
- Article
- ISSN
- 0921-4534
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✦ Synopsis
The systematic variation of the temperature dependence of the second temperature derivative of the electrical resistivity d2p/ dT 2 is reproduced by model calculations, assuming the existence of a narrow conduction band in the vicinity of the Fermi level EF. The analysis of the characteristic features on the d2p/dT 2 vs. Tcurve makes it possible to determine both the half-bandwidth ?'2= (e2--~)/2KB, where ~, e2 are the band edges, and the Fermi level position with respect to the middle of the band T~ = [½ (e~ +~2) --EF]/KB. It is shown that d2p/dT 2 is negative in this model at certain temperatures below T2 if the condition 0.563 T2 < I T~I < T2 is fulfilled, and positive at all temperatures if I T~[ is outside this interval, while dp/dT> 0 in both cases. This fact may be responsible for the complex behaviour of the p (T) dependence caused by the change of composition during the metal-insulator transition in high-To oxides.