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Superconducting properties of iron-containing ternary silicides Lu-Fe-Si

含铁三元硅化物Lu-Fe-Si的超导性能

基本信息

批准号：
61540231
负责人：
OOTA Akio
金额：
$ 1.22万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

Superconductivity has been studied through electrical resistivity, Hall coefficient and AC susceptibility on a series of iron-containing rare earth silicides Lu-Fe-Si around the stoichiometric composition Lu_2Fe_3Si_5. The superconducting transition temperature T_c shows a maximum (-6.0K) on the stoichiometry and decreases with a deviation from itespecially on the Fe-rich side. The upper critical field for Lu_2Fe_3Si_5 increases linearly with decreasing temperature with a slope of about 1.5 Tesla/K, which is nearly the same as the ones for other off-stoichiometic samples in spite of the difference in T_2. All samples show a monotonic increase in resistivity with temperature in the range between T_c and 300K. The resistivity ratio <vho>(300K)/<rho>(6K) equals to -16 for Lu_2Fe_3Si_5 and decreases with a deviation from the stoichiometry especially on the Fe-rich side, which indicates the appearance of disorder in the sample as expected from the result of T_c. All samples show T^2 dependence of resistivity at lowtemperatures, which is interpreted in terms of electron-electron scattering. The carrier concentration of Lu_2Fe_3 obtained from Hall coefficiet is independent of temperature between T_c ad 300K, and is estimated to be 6 x 10^<27> m^<-3>, which is compared with 1 x 10^<27> m^<-3> for another isostructural sample Y_2Fe_3Si_5 with T_c = 2.4K. The difference in T_c between them would be ascribed to the difference of carrier concentration.

通过电阻率、霍尔系数和交流磁化率研究了化学计量比为Lu_2Fe_3Si_5附近的一系列含铁稀土硅化物Lu-Fe-Si的超导电性。超导转变温度T_c在化学计量比上有一个最大值（-6.0K），随着偏离T_c而降低，特别是在富铁侧。Lu_2Fe_3Si_5的上临界场随温度的降低而线性增加，斜率约为1.5Tesla/K，这与其它非化学计量比样品的上临界场几乎相同，尽管T_2不同。在T_c ~ 300 K范围内，所有样品的电阻率随温度的升高而单调增加。Lu_2Fe_3Si_5的电阻率比<vho>（300 K）/<rho>（6 K）为-16，并随着偏离化学计量比而减小，特别是在富铁侧，这表明样品中出现了无序，正如从T_c的结果所预期的那样。所有样品在低温下的电阻率都表现出T^2依赖性，这可以用电子-电子散射来解释。由霍尔系数得到的Lu_2Fe_3的载流子浓度在T_c ~ 300 K之间与温度无关，估计为6 × 10 ~（-3）m <27>~ 2<-3><27>，<-3>而另一个T_c = 2.4K的等结构样品Y_2Fe_3Si_5的载流子浓度为1 × 10 ~（-3）m ~ 2。它们之间的T_c的差异可归因于载流子浓度的差异。