NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ
碩士 === 國立交通大學 === 電子物理系所 === 98 === The roles of Se deficiency and Fe atoms, for the superconductivity of FeSe, have been respectively investigated in FeSe1-δ and (Fe1-xCux)Se1-δ, by our NMR experiments. The data, for nuclear spin-lattice relaxation rate (1/T1), show that the spin fluctuations are w...
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ndltd-TW-098NCTU54290292016-04-18T04:21:39Z http://ndltd.ncl.edu.tw/handle/44986937547506523732 NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ 含鐵超導材料FeSe1-δ與銅摻雜之(Fe1-xCux)Se1-δ的核磁共振研究 Wu, Chia-Chin Jack 吳家慶 碩士 國立交通大學 電子物理系所 98 The roles of Se deficiency and Fe atoms, for the superconductivity of FeSe, have been respectively investigated in FeSe1-δ and (Fe1-xCux)Se1-δ, by our NMR experiments. The data, for nuclear spin-lattice relaxation rate (1/T1), show that the spin fluctuations are weakened at a larger δ, and are correlated with the superconductivity in FeSe. The superconducting volume fraction, estimated by our ac susceptibility experiments, is found to vary inversely with d. Our findings suggest that the Se-deficient FeSe has an inhomogeneous phase, where the superconductivity is associated with the regions having few or no Se vacancies. As for (Fe1-xCux)Se1-δ, Tc is rapidly suppressed by Cu doping and vanishes around x=0.03. The 77Se and 63Cu NMR linewidths suggest that a local moment is induced at the Fe sites, and not at the Cu sites. However, 1/T1 shows no obvious change with the Cu doping. We suspect that other effects, such as disorder or change in the density of states, have more influence on Tc suppression, since a metal-insulator transition, induced by Cu substitution, occurs in the resistivity measurements. Young, Ben-Li 楊本立 2010 學位論文 ; thesis 62 en_US |
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碩士 === 國立交通大學 === 電子物理系所 === 98 === The roles of Se deficiency and Fe atoms, for the superconductivity of FeSe, have been respectively investigated in FeSe1-δ and (Fe1-xCux)Se1-δ, by our NMR experiments. The data, for nuclear spin-lattice relaxation rate (1/T1), show that the spin fluctuations are weakened at a larger δ, and are correlated with the superconductivity in FeSe. The superconducting volume fraction, estimated by our ac susceptibility experiments, is found to vary inversely with d. Our findings suggest that the Se-deficient FeSe has an inhomogeneous phase, where the superconductivity is associated with the regions having few or no Se vacancies. As for (Fe1-xCux)Se1-δ, Tc is rapidly suppressed by Cu doping and vanishes around x=0.03. The 77Se and 63Cu NMR linewidths suggest that a local moment is induced at the Fe sites, and not at the Cu sites. However, 1/T1 shows no obvious change with the Cu doping. We suspect that other effects, such as disorder or change in the density of states, have more influence on Tc suppression, since a metal-insulator transition, induced by Cu substitution, occurs in the resistivity measurements.
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author2 |
Young, Ben-Li |
author_facet |
Young, Ben-Li Wu, Chia-Chin Jack 吳家慶 |
author |
Wu, Chia-Chin Jack 吳家慶 |
spellingShingle |
Wu, Chia-Chin Jack 吳家慶 NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
author_sort |
Wu, Chia-Chin Jack |
title |
NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
title_short |
NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
title_full |
NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
title_fullStr |
NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
title_full_unstemmed |
NMR study of Iron-based superconductor FeSe1-δ and Cu-doped (Fe1-xCux)Se1-δ |
title_sort |
nmr study of iron-based superconductor fese1-δ and cu-doped (fe1-xcux)se1-δ |
publishDate |
2010 |
url |
http://ndltd.ncl.edu.tw/handle/44986937547506523732 |
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