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Magnetic field induced reentrance of superconductivity in the cage-type superconductorY5Rh6Sn18
Physical Review B ( IF 3.2 ) Pub Date : 2021-10-25 , DOI: 10.1103/physrevb.104.165306
M. Fijałkowski 1, 2 , M. M. Maśka 3 , J. Deniszczyk 4 , A. Ślebarski 2, 5
Affiliation  

The morphological and/or chemical disorder is commonly known as detrimental to superconductivity and typically reduces the critical temperature Tc. We present research on the skutterudite-related Y5Rh6Sn18 system, where local atomic disorder leads to novel disorder-enhanced superconductivity. Our present studies focus on the series of Y4.5M0.5Rh6Sn18 compounds, where the metallic dopants M=Ca, Ti, Sr, Zr, La, or Lu, when they are smaller than the atomic radius of Y (the case of Ti, Zr, Lu, or vacancies at the Y sites), generate the so-called peak effect at T<Tc in the fields smaller than the critical field Hc2. The peak effect is well documented experimentally by measurements of the temperature variations in electric transport and ac magnetic susceptibility under external magnetic fields. In accordance with the commonly accepted explanation of the peak effect, we assume that the magnetic field induced reentrance of superconductivity in Y4.5M0.5Rh6Sn18 results from a change in the structure of the vortex lattice close to Hc2. Using a simple theoretical model we argue that the effectiveness of this mechanism can depend on the size of the dopant. We also investigate the band structure properties by x-ray electron spectroscopy and ab initio calculations. It seems interesting that the density functional theory predicts a magnetic moment on the dopant Ti, which is a reason for the Kondo effect, confirmed experimentally.

中文翻译:

笼型超导体Y5Rh6Sn18中超导的磁场诱导折返

形态和/或化学无序通常对超导性有害,通常会降低临界温度 C. 我们介绍了与方钴矿相关的研究5618系统,其中局部原子无序导致新的无序增强超导性。我们目前的研究集中在一系列4.50.5618 化合物,其中金属掺杂剂 =,钛,锶,锆,镧,或Lu,当它们比Y(钛,锆,路,或在Y部位空位的情况下)的原子半径小,产生所谓的峰值效应<C 在小于临界场的场中 HC2. 通过测量外部磁场下电传输和交流磁化率的温度变化,峰值效应在实验中得到了很好的证明。根据对峰值效应的普遍接受的解释,我们假设超导的磁场诱导折返4.50.5618 是由于涡旋晶格结构的变化接近于 HC2. 使用一个简单的理论模型,我们认为这种机制的有效性取决于掺杂剂的大小。我们还通过 X 射线电子能谱和ab initio计算研究了能带结构特性。有趣的是,密度泛函理论预测了掺杂剂 Ti 上的磁矩,这是近藤效应的一个原因,实验证实了这一点。
更新日期:2021-10-26
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