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arXiv 1406.7370cond-mat.supr-concond-mat.str-el
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量子临界超导体中的无序

Disorder in a Quantum Critical Superconductor

S. Seo, Xin Lu, J. -X. Zhu, R. R. Urbano, N. Curro, E. D. Bauer, V. A. Sidorov, L. D. Pham, Tuson Park, Z. Fisk, J. D. Thompson

摘要:

在四类材料中,层状铜氧化物、有机物、铁磷族化合物和重费米子化合物,当磁跃迁被调谐到绝对零度,即磁量子临界点(QCP)时,非常规的超导状态出现。在大多数材料中,QCP通过化学取代或施加压力来实现。CeCoIn5是少数几种天生的量子临界超导体材料之一,因此,它提供了探索化学无序后果的机会。CeCoIn5的镉掺杂晶体是一个特别有趣的情况,其中Cd取代诱导长程磁序,如在Zn掺杂的铜氧化物中。施加的压力在全球范围内抑制镉诱导的磁秩序和恢复体超导性。然而,在这里,我们表明,当地的磁相关性,其空间范围随施加的压力而减小,坚持外推QCP。杂质诱导的磁矩的残留液滴阻止了量子临界性的常规特征的再现,但诱导了异质电子态。这些发现表明,自旋液滴可以是一个来源的电子异质性类的强关联电子系统,并强调需要谨慎的解释时,调谐相关系统的化学取代的影响。

英文摘要:

In four classes of materials, the layered copper-oxides, organics, iron-pnictides and heavy-fermion compounds, an unconventional superconducting state emerges as a magnetic transition is tuned toward absolute zero temperature, that is, toward a magnetic quantum-critical point (QCP). In most materials, the QCP is accessed by chemical substitutions or applied pressure. CeCoIn5 is one of the few materials that are born as a quantum-critical superconductor and, therefore, offers the opportunity to explore the consequences of chemical disorder. Cadmium-doped crystals of CeCoIn5 are a particularly interesting case where Cd substitution induces long-range magnetic order, as in Zn-doped copper-oxides. Applied pressure globally supresses the Cd-induced magnetic order and restores bulk superconductivity. Here we show, however, that local magnetic correlations, whose spatial extent decreases with applied pressure, persist at the extrapolated QCP. The residual droplets of impurity-induced magnetic moments prevent the reappearance of conventional signatures of quantum criticality, but induce a heterogeneous electronic state. These discoveries show that spin droplets can be a source of electronic heterogeneity in classes of strongly correlated electron systems and emphasize the need for caution when interpreting the effects of tuning a correlated system by chemical substitution.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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