Ru and Sn double doping effects on superconductivity of CeCoIn5

• Main Authors: Lo, Yu Kuo, 羅裕國
• Other Authors: Chen,Yang Yuan
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/85755990952769796370

碩士 === 國立政治大學 === 應用物理研究所 === 102 === Heavy fermion system CeCoIn5 exhibits both superconducting and antiferromagnetic states with TC= 2.3 K and TN= 3.8 K respectively. It is a good candidate for the study of quantum critical point (QCP), i.e., the superconducting temperature can be suppressed to zero by doping or external applied pressure, etc. Based on the previous studies, the Sn doped CeCoIn5-xSnx would change the electronic structure and lower its superconducting temperature； Ru doped CeCo1-yRuyIn5 would also linearly decreases its superconducting temperature as well. In this thesis, we tried to double-dope Ru (hole doping) and Sn (electron doping) into CeCoIn5 system and observe its physical properties as the suppressed superconducting temperature approachs to zero by maintaining its number of valance electrons. All CeCoIn5 single crystals are synthesized by indium-flux method, and their single-phase crystal structures are confirmed by X-ray powder diffraction analysis. The magnetic susceptibility data measured by the Superconducting Quantum Interference Device Magnetometer (SQUID) shows the superconducting behavior and the quality of these single crystals. Moreover, the electrical resistivity and the specific heat measurements indicate the decreasing of the superconducting temperature. The un-doped sample CeCoIn5, TC is 2.3 K, whereas the superconducting temperature of Ru-doped sample (CeCo0.8Ru0.2In5) is dereeased toward 2.2 K. However, for the double-doped sample of CeCo0.8Ru0.2In4.9Sn0.1, its superconducting temperature is decreased to 1.53 K, which is greatly decreased as compared with the un-doped or single doped specimens. Obviously to suppress the superconducting temperature to zero, other parameters such as external pressure or applied magnetic field etc. are required.