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Coexistence of superconductivity and magnetic order in rare-earth compounds.

稀土化合物中超导性与磁序的共存。

基本信息

批准号：
10640337
负责人：
DONNI Andreas
金额：
$ 1.86万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

Coexistence of superconductivity and magnetic order has been reported for the cubic Heusler alloys ErPdィイD22ィエD2Sn (Tc = 1.17 K, TィイD2NィエD2 = 1.0 K) and YbPdィイD22ィエD2Sn (Tc = 2.3 K, TィイD2NィエD2 = 0.22 K). We have prepared a polycrystalline YbPdィイD22ィエD2Sn sample, investigated the superconducting transition by electrical resistivity, magnetic ac susceptibility and specific heat experiments and performed low temperature neutron diffraction experiments down to 30 mK to determine the kind of magnetic structure that coexists with superconductivity. The results showed that the magnetic structures that coexist with superconductivity are different for ErPdィイD22ィエD2Sn (FCC-type II antiferromagnet, k=[1/2, 1/2, 1/2] with an additional incommensurate component) and for YbPdィイD22ィエD2Sn (FCC type I antiferromagnet, k=[0, 0, 1], with no incommensurate component).For the high-temperature superconductors RィイD22ィエD2BaィイD24ィエD2CuィイD27ィエD2OィイD215-δィエD2(R=Dy,Er) we have used the sol gel technique to prepar … More e large amounts (over 3 cmィイD13ィエD1) of single phase samples. By systematic measurements of the low temperature specific heat we have studied the long- and short-range magnetic rare-earth interactions which coexist with superconductivity as a function of the rare-earth element (R) and of the oxygen content (δ). According to our specific heat results, changing the oxygen concentration in Er247 samples from a high or a low value to an intermediate value causes a larger in-plane anisotropy and tends to lower dimensionality and correlation range of the magnetic interactions of the ErィイD13+ィエD1 ions. Such an effect is not observed for the Dy247 samples, where the specific heat anomaly at TィイD2NィエD2 = 1.0 K is found to be almost independent of the oxygen concentration except for a small broadening for the sample DyィイD22ィエD2BaィイD24ィエD2CuィイD27ィエD2OィイD214.45ィエD2 with intermediate oxygen content, where electronic disorder in the CuOィイD22ィエD2-planes causes some disorder in the exchange interactions. Less

本文报道了立方Heusler合金ErPd D22 D2 Sn（Tc = 1.17 K，T D2 N D2 = 1.0 K）和YbPd D22 D2 Sn（Tc = 2.3 K，T D2 N D2 = 0.22 K）的超导电性和磁有序性的共存。我们制备了多晶YbPd_xD_22_xD_2Sn样品，通过电阻率、磁化率和比热实验研究了超导转变，并进行了低至30 mK的低温中子衍射实验，以确定与超导性共存的磁性结构。结果表明，ErPd_（12）D_22_（12）D_2Sn的超导磁结构是不同的（FCC-II型反铁磁体，k=[1/2，1/2，1/2]，具有额外的无公度分量）和对于YbPd D22 D2 Sn（FCC I型反铁磁体，k=[0，0，1]，对于高温超导体R_（10）D_（22）Ba_（10）D_（24）Cu_（10）D_（27）O_（10）D_（215-δ）Cu_（10）D_（22）（R=Dy，Er），我们用溶胶-凝胶法制备了具有良好电性能的超导体。 ...更多信息 e大量（超过3 cm厚D13 cm厚D1）单相样品。通过系统测量低温比热，我们研究了与超导性共存的长程和短程磁性稀土相互作用与稀土元素（R）和氧含量（δ）的函数关系。根据我们的比热结果，改变Er 247样品中的氧浓度从一个高或低值到一个中间值导致较大的面内各向异性，并倾向于降低的维度和相关范围的Er 247 D13+ Er 247 D1离子的磁相互作用。在Dy 247样品中没有观察到这种效应，发现在T = 1.0 K时的比热异常几乎与氧浓度无关，除了具有中等氧含量的样品Dy 247 D22 Ba 247 D24 Cu 247 D27 Ba 247 D214.45 Ba 247 D214.45 Ba 247 D214.45 Ba 247 D214.45 Ba 247 D2147 D214.45 Ba 247 D2147 D214.45其中，在CuO-D22-D2-平面中的电子无序引起交换相互作用中的某些无序。少