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

• 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
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15540347/
• 关键词: filled skutterudite; highly correlated electron syste; heavy fermion superconductor; thermoelectric material; high-quality single crystal; electronic transport properties; magnetism; metal-insulator transition; ドハース・ファンアルフェン効果

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

我们已经准备了填充的Skutterudite rt_4x_ <12>的高质量单晶（r =稀土，t = fe，ru，os，os，x = p，as，sb），并研究了异常的物理特性。主要结果总结如下。1。我们从中证实了pr^3+的晶体电场（CEF）基态为γ_1单元。从非弹性中子衍射实验中，我们发现了超导过渡温度以下磁兴奋的线宽度的狭窄，这表明超导性与兴奋之间的紧密联系。 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费米表面（FS）。我们发现LARU_4P_ <12>的FS与PRRU_4P_ <12>计算出的FS的FS基本相同，这与PRRU_4P_ <12>中4F电子的局部性质一致。考虑到LARU_4P_ <12>未显示M-I转变，我们指出了4F-和传导电子与FS嵌套在驱动Prru_4p_ <12>的M-I转变方面相关的基本作用。从非弹性中子衍射实验中，我们发现，远低于M-1过渡温度的4F电子状态被描述为明确定义的CEF兴奋，即，两个不同的PR位置相互不同，这解释了磁性。压力温度相图中铁磁临界点的附近来自压力下的电阻测量值。对于其他填充的Skutterudites，例如SMRU_4P_ <12>（M-I过渡），CEOS_4SB_ <12>（Kondo半导体）（Kondo半导体）等。 μSR，NMR。 NQR，光发射，光学传导率，弹性，Mossbauer和Ramman散射实验正在进行中，以阐明异常物理特性的起源。较少的

项目成果

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。

Magnetic Excitation in Heavy-Fermion Superconductor PrOs_4Sb_<12>

重费米子超导体 PrOs_4Sb_<12> 中的磁激发

• 发表时间: 2004
• 期刊: Journal of Physical Society of Japan Vol.73, No.6
• 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。

Fermi Surface of LaRu_4P_<12> : A Clue to the Origin of the Metal-insulator Transition in PrRu_4P_<12>

LaRu_4P_<12> 的费米面：PrRu_4P_<12> 金属-绝缘体转变起源的线索

• 发表时间: 2005
• 期刊: Phys. Rev. B 71
• 作者: A.Yoshimi;H.Ueno et al.;H.Harima;S.Kimura;S.Kimura;H.Harima;S.R.Saha
• 通讯作者: S.R.Saha

Evolution of 4f electron states in the metal-insulater transition of PrRu_4P_12

PrRu_4P_12金属-绝缘体转变中4f电子态的演化

• 发表时间: 2005
• 期刊: Physical Review B Vol.72・No.2 (5pages)
• 作者: S.R.Saha et al.;K.Iwasa et al.
• 通讯作者: K.Iwasa et al.