Thermal Fluctuation and Upper Critical Field of La0.18Ca0.82(FeAs)2 Superconducting Single Crystal.
碩士 === 國立中興大學 === 奈米科學研究所 === 101 === We have studied the thermal fluctuation effect on the transport properties of Ca0.18La0.82(FeAs)2 system. The single crystals of Ca1-xLax(FeAs)2 were grown by the FeAs self-flux method. The Ca(FeAs)2 has I4/mmm Th(CrSi)2 –type crystal structure. The resistiv...
| Main Authors: | , |
|---|---|
| Other Authors: | |
| Format: | Others |
| Language: | zh-TW |
| Published: |
2013
|
| Online Access: | http://ndltd.ncl.edu.tw/handle/qyh2j4 |
| Summary: | 碩士 === 國立中興大學 === 奈米科學研究所 === 101 === We have studied the thermal fluctuation effect on the transport properties of Ca0.18La0.82(FeAs)2 system. The single crystals of Ca1-xLax(FeAs)2 were grown by the FeAs self-flux method. The Ca(FeAs)2 has I4/mmm Th(CrSi)2 –type crystal structure. The resistivity shows metallic behavior in the normal state with the linear temperature dependence.
As replacing Ca+2 by La3+ ion, the electron density increases in the FeAs layer via the charge transference, and the lattice constant of c-axis becomes longer. The results led to the superconductivity.
The superconducting transition width broadened by the external magnetic field and the thermal fluctuation magnetoconductivity can be scaled by a universal function for all applied magnetic fields. The upper critical fields Hc2 are thus determined by the scaling analysis of the thermal fluctuation conductivity. The formula gives an excellent fit to the data. Based on the value of upper critical field Hc2(0), the superconducting coherence length is determined. We found that the lower critical field is abnormally small of 1 gauss.
|
|---|