NdOFe1-xRhxAs和(La1-xBix)0.85Na0.15MnO3的磁性和输运性质.pdf

摘 要 继 20 世纪 80 年代铜氧化物高温超导体发现之后，铁基超导体的发现给探 索超导机制，研究超导起源以及应用提供了更多的研究机会。本文研究了磁性 离子Rh掺杂对NdFeAsO体系磁性及输运性质的影响，以此讨论铁基超导体中磁 性与超导之间的联系。我们通过固相反应制备NdFe Rh AsO系列样品，并进行 1-x x 物理性质的测量。样品的母体在 147 K发生结构相变，同时伴随着反铁磁相变。 Rh离子的掺杂压制了结构相变和反铁磁相变，在掺杂浓度x = 0.05 时进入超导 态，并在x = 0.10 时达到最高超导温度 13 K。样品中并未发现超导态与反铁磁 态的共存现象。 本文同时研究了Bi离子掺杂对La Na MnO 的影响。利用溶胶—凝胶法 0.85 0.15 3 制备出样品后，我们发现Bi离子的掺杂可以促进样品晶粒的形成。虽然没有改 变样品中Mn3+/Mn4+ ，但Bi离子依然压制了样品的铁磁性，降低了TC 。同时，样 品的电阻率随掺杂浓度的增加而迅速增加，且在高掺杂区域发现了较高的磁电 阻效应。 关键词：铁基超导体；超导电性；锰氧化物；巨磁电阻效应 I Abstract More research opportunities are given to analyze the mechanism, origin and application of superconductors by the newly discovered Fe-based superconductors, after the copper oxide superconductors in 1980s. This paper studied the magnetic and transport properties of Rh-doped NdFeAsO, in order to find the relationship between superconductivity and magnetism. We synthesized NdFe Rh AsO by a 1-x x solid reaction method, and measured the physical properties. We found a structural phase transition at 147 K in the undoped NdFeAsO samples which is followed by an antiferromagnetic transition. Rh doping in NdFeAsO suppresses the structural and magnetic phase transition, and induces the superconducting transition when the doping content came to 0.05, and a maximum T = 13 K was achieved in the x = 0.1 C sample. The coexistence of superconductivity and antiferromagnetic phase was not