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Study of exotic superconductivity in the iron-family-based intermetallic compounds

铁族金属间化合物奇异超导性研究

基本信息

批准号：
21740266
负责人：
WATANABE Tadataka
金额：
$ 2.33万
依托单位：
Nihon University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Young Scientists (B)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

项目摘要

This project performed studies of exotic superconductivity and geometrical frustration effects in several iron-family-based compounds. And remarkable research results were obtained especially in the study of exotic superconductivity in the iron silicide Lu_2Fe_3Si_5, and the study of geometrical frustration effects in The spinel cobaltite GeCo_2O_4.The iron silicide superconductor Lu_2Fe_3Si_5 has three-dimensional multiband structure which is demarcated from the multiband structure in the iron arsenide superconductors. This project performed study of non-magnetic impurity effects on the superconductivity, and magneto-thermal transport experiments in Lu_2Fe_3Si_5. And we obtained research results which strongly suggest the sign-reversed multigap superconductivity.The spinel cobaltite GeCo_2O_4 is a geometrically-frustrated magnet with orbital degrees of freedom, where an antiferromagnetic transition occurs despite the dominance of ferromagnetic exchange interactions. Inelastic neutron scattering experimets in GeCo_2O_4 observed a typical frustration effect of molecular spin excitations. Furthermore, ultrasound velocity measuremets in GeCo_2O_4 observed elastic anomalies driven by the molecular spin excitations, and elastic anomalies which strongly suggest the occurrence of magnetic-field induced orbital order-order transitions.

该项目研究了几种铁系化合物的奇异超导电性和几何受挫效应。特别是在硅化铁Lu_2Fe_3Si_5的奇异超导电性和尖晶石钴矿GeCoO_2O_4的几何受挫效应的研究方面，取得了显著的研究成果。本项目研究了非磁性杂质对Lu_2Fe_3Si_5超导电性的影响，并进行了磁热输运实验。我们的研究结果有力地表明了多禁带超导的符号反转性质。尖晶石钴氧化物GCoO_2O_4是一种几何受阻的具有轨道自由度的磁体，尽管铁磁交换作用占主导地位，但仍发生了反铁磁相变。在GeCoO_2O_4中的非弹性中子散射实验中观察到了典型的分子自旋激发受挫效应。此外，在GeCoO_2O_4中的超声测速观测到了由分子自旋激发驱动的弹性反常，以及强烈暗示发生了磁场诱导的轨道有序-有序跃迁的弹性反常。