Emergent exotic superconductivity in artificially engineered tricolor Kondo superlattices
Emergent exotic superconductivity in artificially engineered tricolor Kondo superlattices
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DOI：
10.1103/physrevb.96.174512
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发表时间：
2017-11-16
影响因子：
3.7
通讯作者：
Kasahara, Y.
中科院分区：
文献类型：
--
作者：
Naritsuka, M.;Ishii, T.;Kasahara, Y.
在寻找奇异的超导配对态的过程中，拉什巴效应引起了人们的极大兴趣。拉什巴效应在反转对称性破缺的情况下，由于强烈的自旋-轨道相互作用(SOI)而提高了电子-自旋简并。在这里，为了将拉什巴效应引入到二维强关联电子系统中，我们制备了由三种原子厚度的f电子化合物组成的非中心对称(三色)超晶格：d波重费米子超导体CeCoIn5夹在两种不同的非磁性金属YbCoIn5和YbRhIn5中。我们发现，Rashba SOI在这些三色近藤超晶格中诱导的全局反转对称性破缺导致了CeCoIn5超导性质的深刻变化，这表现在上临界场的反常温度和角度依赖关系，这与块体CeCoIn5单晶形成了鲜明的对比。我们证明了2DCeCoIn5块层中的Rashba效应可以通过改变层的厚度来调节。此外，面内上临界场的温度依赖关系在低温下表现出反常的上升，这归因于可能出现螺旋状或条状超导相。我们的结果表明，三色近藤超晶格为探索具有Rashba效应的强关联2D电子系统中的奇异超导态提供了一个新的平台。
In the quest for exotic superconducting pairing states, the Rashba effect, which lifts the electron-spin degeneracy as a consequence of strong spin-orbit interaction (SOI) under broken inversion symmetry, has attracted considerable interest. Here, to introduce the Rashba effect into two-dimensional (2D) strongly correlated electron systems, we fabricate noncentrosymmetric (tricolor) superlattices composed of three kinds of f-electron compounds with atomic thickness; d-wave heavy fermion superconductor CeCoIn5 sandwiched by two different nonmagnetic metals, YbCoIn5 and YbRhIn5. We find that the Rashba SOI-induced global inversion symmetry breaking in these tricolor Kondo superlattices leads to profound changes in the superconducting properties of CeCoIn5, which are revealed by unusual temperature and angular dependencies of upper critical fields that are in marked contrast with the bulk CeCoIn5 single crystals. We demonstrate that the Rashba effect incorporated into 2D CeCoIn5 block layers is largely tunable by changing the layer thickness. Moreover, the temperature dependence of in-plane upper critical field exhibits an anomalous upturn at low temperatures, which is attributed to a possible emergence of a helical or stripe superconducting phase. Our results demonstrate that the tricolor Kondo superlattices provide a new playground for exploring exotic superconducting states in the strongly correlated 2D electron systems with the Rashba effect.