Low temperature specific heat (LTSH) is a powerful tool to investigate the physical properties of bulk samples. For superconductivity, LTSH can probe the pairing state in superconductors and provides additional information under magnetic fields. In this thesis, I present comprehensive specific-heat studies of superconductivity in YNi2B2C, NbSe2, and CeRu2. (1) Single crystalline YNi2B2C was found to be superconducting at the superconducting transition temperature Tc ~ 13.77 K. The superconducting specific heat Ce(T) can be described by either the point-node or the two-gap model. (2) Single crystalline NbSe2 has a two-dimensional crystalline structure showing the Tc ~ 6.7 K and the anisotropy in the critical fields, Hc2¡æ/Hc2// ~3. We investigated the Ce(T) and the electronic specific heat £^(H) by the two-gap model. Obtained fitting parameters, such as gap values and the relative ratio of two gaps in both analyses (Ce(T) and £^(H)), are comparable meaning that the superconductivity of NbSe2 can be described by the two-gap scenario. (3) Finally, we studied the DC magnetic susceptibility and the specific heat of polycrystalline CeRu2 in different magnetic fields. In the bulk CeRu2, the amount of the possible impurity phase or nano-clusters was reduced after annealing. Based on the analysis results of zero-field and in-field specific heat, CeRu2 is a BCS-like superconductor with an anisotropic gap.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0629109-204050 |
| Date | 29 June 2009 |
| Creators | Huang, Chien-lung |
| Contributors | Hsiung Chou, Quark Chen, Yung- Kang Kuo, Hung-Duen Yang, Yang-Yuan Chen, Chin-Shan Lue, Jiunn-Yuan Lin |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0629109-204050 |
| Rights | unrestricted, Copyright information available at source archive |
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