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High-purity single-crystal growth and the research of heavy fermion superconductivity in Pr-based filled skutterudites

镨基填充方钴矿高纯单晶生长及重费米子超导研究

基本信息

批准号：
15540347
负责人：
SUGAWARA Hitoshi
金额：
$ 2.37万
依托单位：
The University of Tokushima (2004-2005)Tokyo Metropolitan University (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

We have prepared the high-quality single crystals of filled skutterudite RT_4X_<12> (R=rare earth, T=Fe,Ru,Os,X=P,As,Sb) and investigated the anomalous physical properties. Main results are summarized as below.1.Heavy fermion superconductivity of PrOs_4Sb_<12>2.Metal-insulator (M-I) transition of PrRu_4P_<12>3.Unusual heavy fermion state of SmOs_4Sb_<12>About PrOs_4Sb_<12>, we have measured the magnetoresistance for field along the three principal field directions and determined the magnetic field-temperature phases, from which we have confirmed the crystal electric field (CEF) ground state of Pr^3+ to be Γ_1 singlet. From inelastic neutron diffraction experiments, we have found the narrowing of the line widths of the magnetic excitations below the superconducting transition temperature, which is suggested the close connection between the superconductivity and the excitations. From the thermal conductivity measurements, we have found an anomalous feature of magnetic field dependence, f … More rom which we have proposed the multi band superconductivity of PrOs_4Sb_<12>.About PrRu_4P_<12>, to clarify the origin of M-I transition, we have measured the de Haas-van Alphen (dHvA) effect of the reference compound LaRu_4P_<12> and determined the Fermi surface (FS). We have found that the FS of LaRu_4P_<12> is basically the same with that of calculated FS of PrRu_4P_<12>, that is consistent with the localized nature of 4f electrons in PrRu_4P_<12>. Taking into account that LaRu_4P_<12> does not show the M-I transition, we have pointed out the essential role of correlation between the 4f- and conduction electrons cooperating with the FS nesting in driving the M-I transition of PrRu_4P_<12>. From inelastic neutron diffraction experiments, we have found that the 4f electron state far below the M-I transition temperature is described as well-defined CEF excitations, i.e., two different Pr-sites have different CEF each other, which explains the magnetic properties.About SmOs_4Sb_<12>, we have confirmed the bulk ferromagnetism below 3 K from NQR measurement, and found that this compounds is situated at the vicinity of ferromagnetic critical point in the pressure-temperature phase diagram from the resistivity measurements under pressure.For other filled skutterudites, such as SmRu_4P_<12> (M-I transition), CeOs_4Sb_<12> (Kondo semiconductor) etc., various experiments, such as electronic transport, dHvA effect, thermal and magnetic experiments, neutron diffraction, μSR,NMR. NQR, photoemission, optical conductivity, elastic, Mossbauer and Ramman scattering experiments are in progress to clarify the origin of the anomalous physical properties. Less

制备了高质量的填型方角石RT_4X_<12> （R=稀土，T=Fe,Ru,Os，X=P,As,Sb）单晶，并对其异常物理性质进行了研究。主要结果总结如下：1。PrOs_4Sb_<12 bbb_的重费米子超导性PrRu_4P_<12 bbb_的金属-绝缘子（M-I）跃迁关于PrOs_4Sb_<12>，我们沿着三个主要的场方向测量了场的磁电阻，并确定了磁场-温度相，由此确定了Pr^3+的晶体电场（CEF）基态为Γ_1单重态。从非弹性中子衍射实验中，我们发现在超导转变温度以下，磁激励的线宽变窄，这表明超导性与激励之间有密切的联系。从热导率测量中，我们发现了磁场依赖的反常特征，并由此提出了PrOs_4Sb_<12>的多带超导性。对于PrRu_4P_<12>，为了明确M-I跃迁的起源，我们测量了参考化合物LaRu_4P_<12>的de Haas-van Alphen （dHvA）效应，并确定了费米表面（FS）。我们发现LaRu_4P_<12>的FS与PrRu_4P_<12>的计算FS基本一致，这与PrRu_4P_<12>中4f电子的局域性是一致的。考虑到LaRu_4P_<12>未表现出M-I跃迁，我们指出了4f-和传导电子之间的相关性与FS嵌套配合在驱动PrRu_4P_<12>的M-I跃迁中的重要作用。从非弹性中子衍射实验中，我们发现远低于M-I转变温度的4f电子态被描述为定义良好的CEF激发，即两个不同的pr -位彼此具有不同的CEF，这解释了磁性。对于SmOs_4Sb_<12>，我们通过NQR测量确认了该化合物在3 K以下的整体铁磁性，并通过压力下电阻率测量发现该化合物位于压力-温度相图的铁磁性临界点附近。对其他填态方晶石，如SmRu_4P_<12> （M-I跃迁）、CeOs_4Sb_<12>（近东半导体）等，进行了电子输运、dHvA效应、热磁实验、中子衍射、μSR、NMR等实验。NQR、光电发射、光电导率、弹性、穆斯堡尔和拉曼散射实验正在进行，以澄清异常物理性质的起源。少

项目成果

期刊论文数量（50）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

T.Tayama et al.: "Magnetic Phase Diagram of the Heavy Fermion Superconductor PrOs_4Sb_<12>"Journal of Physical Society of Japan. Vol.72, No.6. 1516-1522 (2003)

T.Tayama等人：“重费米子超导体PrOs_4Sb_<12>的磁相图”日本物理学会杂志。

DOI：
发表时间：
期刊：
影响因子：
0
作者：
通讯作者：

Magnetic Excitation in Heavy-Fermion Superconductor PrOs_4Sb_<12>

重费米子超导体 PrOs_4Sb_<12> 中的磁激发

DOI：
发表时间：
2004
期刊：
Journal of Physical Society of Japan Vol.73, No.6
影响因子：
0
作者：
S.R.Saha et al.;K.Iwasa et al.;H.Sugawara et al.;H.Kotegawa et al.;K.Kuwahara et al.;G.Seyfarth et al.;S.R.Saha et al.;K.Iwasa et al.;H.Sugawara et al.;H.Kotegawa et al.;K.Kuwahara et al.;G.Seyfarth et al.;K.Kuwahara et al.;Y.Aoki et al.;S.Sanada et al.;H.Hidaka et al.;A.D.Huxley et al.;K.Kuwahara et al.
通讯作者：
K.Kuwahara et al.

M.Kohgi et al.: "Evidence for Magnetic-field-induced Ordering in the Heavy Fermion Superconductor PrOs_4Sb_<12>"Journal of Physical Society of Japan. Vol.72, No.5. 1002-1005 (2003)

M.Kohgi 等人：“重费米子超导体 PrOs_4Sb_<12> 中磁场诱导有序化的证据”日本物理学会杂志。