Low-Temperature Anomaly in Thermal Conductivity of Bi2Sr2Ca(Cu1−xNix)2O8: Second Superconducting Phase?
R. Movshovich, M. A. Hubbard, M. B. Salamon, A. V. Balatsky, R. Yoshizaki, J. L. Sarrao, M. Jaime
DOI 10.1103/PhysRevLett.80.1968 · Physical Review Letters
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Abstract
We report the discovery of a low-temperature anomaly in thermal conductivity of Bi2Sr2Ca(Cu1−xNix)2O8 high-temperature superconductor. This anomaly manifests itself as a sharp reduction of the thermal conductivity of the samples at a temperature Tc*≈200mK. The temperature dependence of the thermal conductivity changes dramatically from Tα with α between 1.6 and 1.75 above Tc* to T-linear behavior below it. Application of a small magnetic field suppresses the low-temperature anomaly. We propose that such behavior is consistent with a phase transition into a second bulk low-temperature superconducting state at Tc*. The presence of a second superconducting state would constitute direct evidence for unconventional superconductivity in Bi2Sr2CaCu2O8. Within the suggested scenario, time-reversal symmetry is likely to be violated in the low-temperature phase.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Bi2Sr2Ca(Cu1-xNix)2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 0.2 | Pressure not reported | onset |
| Bi2Sr2CaCu2O8 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 89 | Pressure not reported | unknown |
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