Full-Gap Superconductivity Robust against Disorder in Heavy-Fermion CeCu_{2}Si_{2}.
Full-Gap Superconductivity Robust against Disorder in Heavy-Fermion CeCu_{2}Si_{2}.
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DOI：
10.1103/physrevlett.119.077001
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发表时间：
2017-05
影响因子：
8.6
通讯作者：
T. Takenaka;Y. Mizukami;J. Wilcox;M. Konczykowski;S. Seiro;C. Geibel;Y. Tokiwa;Y. Tokiwa;Y. Kasahara;C. Putzke;Y. Matsuda;A. Carrington;T. Shibauchi
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文献类型：
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作者：
T. Takenaka;Y. Mizukami;J. Wilcox;M. Konczykowski;S. Seiro;C. Geibel;Y. Tokiwa;Y. Tokiwa;Y. Kasahara;C. Putzke;Y. Matsuda;A. Carrington;T. Shibauchi
反铁磁自旋涨落机制非常规配对的一个关键方面是超导能隙在费米表面的不同部分必须具有相反的符号。最近对重费米子超导体 CeCu_{2}Si_{2} 中非节点间隙结构的观察非常令人惊讶，因为这种材料长期以来一直被认为是磁介导库珀配对的超导体的原型示例。在这里，我们研究了电子辐照引入的受控点缺陷对 CeCu_{2}Si_{2} 中随温度变化的磁穿透深度 λ(T) 的影响。我们发现完全带隙态对于无序具有很强的鲁棒性，这证明了符号变化带隙结构所预期的低能束缚态不是由非磁性杂质引起的。这为没有符号反转的 s_{++} 波超导性提供了大量证据。
A key aspect of unconventional pairing by the antiferromagnetic spin-fluctuation mechanism is that the superconducting energy gap must have the opposite sign on different parts of the Fermi surface. Recent observations of non-nodal gap structure in the heavy-fermion superconductor CeCu_{2}Si_{2} were then very surprising, given that this material has long been considered a prototypical example of a superconductor where the Cooper pairing is magnetically mediated. Here we present a study of the effect of controlled point defects, introduced by electron irradiation, on the temperature-dependent magnetic penetration depth λ(T) in CeCu_{2}Si_{2}. We find that the fully gapped state is robust against disorder, demonstrating that low-energy bound states, expected for sign-changing gap structures, are not induced by nonmagnetic impurities. This provides bulk evidence for s_{++}-wave superconductivity without sign reversal.