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The Effects of Annealing URu2Si2 on the Resistivity and Meissner Effect

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dc.contributor.author Pan, Yang
dc.date.accessioned 2012-09-18T15:32:00Z
dc.date.available 2012-09-18T15:32:00Z
dc.date.issued 2012-09-18
dc.identifier.uri http://hdl.handle.net/10464/4107
dc.description.abstract The enigmatic heavy fermion URu2Si2, which is the subject of this thesis, has attracted intensive theoretical and experimental research since 1984 when it was firstly reported by Schlabitz et al. at a conference [1]. The previous bulk property measurements clearly showed that one second order phase transition occurs at the Hidden Order temperature THO ≈ 17.5 K and another second order phase transition, the superconducting transition, occurs at Tc ≈ 1 K. Though twenty eight years have passed, the mechanisms behind these two phase transitions are still not clear to researchers. Perfect crystals do not exist. Different kinds of crystal defects can have considerable effects on the crystalline properties. Some of these defects can be eliminated, and hence the crystalline quality improved, by annealing. Previous publications showed that some bulk properties of URu2Si2 exhibited significant differences between as-grown samples and annealed samples. The present study shows that the annealing of URu2Si2 has some considerable effects on the resistivity and the DC magnetization. The effects of annealing on the resistivity are characterized by examining how the Residual Resistivity Ratio (RRR), the fitting parameters to an expression for the temperature dependence of the resistivity, the temperatures of the local maximum and local minimum of the resistivity at the Hidden Order phase transition and the Hidden Order Transition Width ∆THO change after annealing. The plots of one key fitting parameter, the onset temperature of the Hidden Order transition and ∆THO vs RRR are compared with those of Matsuda et al. [2]. Different media used to mount samples have some impact on how effectively the samples are cooled because the media have different thermal conductivity. The DC magnetization around the superconducting transition is presented for one unannealed sample under fields of 25 Oe and 50 Oe and one annealed sample under fields of 0 Oe and 25 Oe. The DC field dependent magnetization of the annealed Sample1-1 shows a typical field dependence of a Type-II superconductor. The lower critical field Hc1 is relatively high, which may be due to flux pinning by the crystal defects. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Annealing en_US
dc.subject URu2Si2 en_US
dc.subject Resistivity en_US
dc.subject Mounting media en_US
dc.subject Meissner effect en_US
dc.title The Effects of Annealing URu2Si2 on the Resistivity and Meissner Effect en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Physics en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Physics en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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