Exotic heavy-fermion superconductivity in atomically thin CeCoIn5 films
Exotic heavy-fermion superconductivity in atomically thin CeCoIn5 films
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DOI：
10.1103/physrevb.107.l041101
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发表时间：
2023-01
影响因子：
3.7
通讯作者：
L. Peng;M. Naritsuka;S. Akutagawa;S. Suetsugu;M. Haze;Y. Kasahara;T. Terashima;R. Peters;Y. Matsuda;T. Asaba
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文献类型：
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作者：
L. Peng;M. Naritsuka;S. Akutagawa;S. Suetsugu;M. Haze;Y. Kasahara;T. Terashima;R. Peters;Y. Matsuda;T. Asaba
本文报道了用扫描隧道显微镜对CeCoIn$_5$原子级薄膜（一种d$波重费米子超导体）的原位研究。即使在单层CeCoIn$_5$中观察到杂化和超导间隙，提供了由纯二维玻色子激发介导的重准粒子超导性的直接证据。在这些原子级薄膜中，$T_c$被抑制到本体的近一半，但类似于包含具有与薄膜相同厚度的CeCoIn$_5$层的CeCoIn$_5$/YbCoIn$_5$超晶格。值得注意的是，在零温度下的面外上临界场$\mu_0H_{c2\perp}$大大增强了体和超晶格。增强的$H_{c2\perp}$远远超过了泡利和体轨道极限，表明可能出现不寻常的超导性与宇称混合引起的反转对称性破缺。
We report an {\it in-situ} scanning tunneling microscopy study of atomically thin films of CeCoIn$_5$, a $d$-wave heavy-fermion superconductor. Both hybridization and superconducting gaps are observed even in monolayer CeCoIn$_5$, providing direct evidence of superconductivity of heavy quasiparticles mediated by purely two-dimensional bosonic excitations. In these atomically thin films, $T_c$ is suppressed to nearly half of the bulk, but is similar to CeCoIn$_5$/YbCoIn$_5$ superlattices containing CeCoIn$_5$ layers with the same thickness as the thin films. Remarkably, the out-of-plane upper critical field $\mu_0H_{c2\perp}$ at zero temperature is largely enhanced from those of bulk and superlattices. The enhanced $H_{c2\perp}$ well exceeds the Pauli and bulk orbital limits, suggesting the possible emergence of unusual superconductivity with parity mixing caused by the inversion symmetry breaking.