Strong correlation between low energy excitations and superconducting pairing in Yba2Cu3O7-δ
| Autor: | K. A. Mirza, W. Y. Liang, J. W. Loram |
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| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Phase Transitions. 41:45-52 |
| ISSN: | 1029-0338 0141-1594 |
| DOI: | 10.1080/01411599308207758 |
| Popis: | A high precision differential technique is used to measure the specific heat of YBa2Cu3O7-δ for 0 ≤ ∂ ≤ 0.68 between 1.8 K and 300 K against YBa2(Cu0.93Zn0.07)3O7-δ∗ as reference, where δ∗ = 0 or 0.47. Anomalies at the superconducting transition temperature T c are observed for 0 ≤ ∂ ≤ 0.54. Careful analysis of our results show that the electronic specific heat coefficient γ(T) increases from a value close to zero at low temperatures to around 1.7 mJ/g at K2 above 200 K for all values of δ investigated. This is in contrast to the behaviour observed in Zn doped YBa2(Cu1-x Zn x )3O7 for which γ(0) increases with x to saturate at the value of normal metallic YBa2Cu3O7. These results suggest that strong magnetic correlation in the CuO2 layer is responsible for the formation of a low energy spin bound state in the insulating end of the oxygen or hole depleted YBa2Cu3O7-δ series, which is gradually replaced by the formation of the superconducting bound state as the number of hole carriers increases. Do... |
| Databáze: | OpenAIRE |
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