FeSe0.45Te0.55 超导体中不存在 BCS-BEC 交叉

IF 1.5 4区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Chinese Physics B Pub Date : 2024-07-01 DOI:10.1088/1674-1056/ad51f9

Junjie Jia, Yadong Gu, Chaohui Yin, Yingjie Shu, Yiwen Chen, Jumin Shi, Xing Zhang, Hao Chen, Taimin Miao, Xiaolin Ren, Bo Liang, Wenpei Zhu, Neng Cai, Fengfeng Zhang, Shenjin Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Zuyan Xu, Hanqing Mao, Guodong Liu, Zhian Ren, Lin Zhao, Xing-Jiang Zhou

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引用次数: 0

摘要

在铁基超导体 Fe(Se,Te)中，人们在超导态的布里渊区中心附近观察到靠近费米级的扁平带状特征。这是否是超导体中存在 BCS-BEC [巴丁-库珀-施里弗（BCS）、玻色-爱因斯坦凝聚（BEC）] 交叉的证据，目前还存在争议。为了解决这个问题，我们对 FeSe0.45Te0.55 超导体的高质量单晶体进行了高分辨率激光角度分辨光发射测量。通过采用不同的偏振几何结构，我们解析并分离了掺杂带和拓扑表面带，从而有可能分别研究它们的超导行为。在超导状态下，单独的掺杂带并不形成平坦的带状特征，测量到的色散可以很好地用 BCS 图描述。我们发现，在超导状态下，平坦带状特征是由 dyz 带和拓扑表面态带共同形成的。这些结果揭示了扁带状特征的起源，并排除了铁(Se,Te)超导体中存在 BCS-BEC 交叉的可能性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Absence of BCS–BEC crossover in FeSe0.45Te0.55 superconductor

In iron-based superconductor Fe(Se,Te), a flat band-like feature near the Fermi level was observed around the Brillouin zone center in the superconducting state. It is under debate whether this is the evidence on the presence of the BCS–BEC [Bardeen–Cooper–Schrieffer (BCS), Bose–Einstein condensation (BEC)] crossover in the superconductor. High-resolution laser-based angle-resolved photoemission measurements are carried out on high quality single crystals of FeSe_0.45Te_0.55 superconductor to address the issue. By employing different polarization geometries, we have resolved and isolated the d_yz band and the topological surface band, making it possible to study their superconducting behaviors separately. The d_yz band alone does not form a flat band-like feature in the superconducting state and the measured dispersion can be well described by the BCS picture. We find that the flat band-like feature is formed from the combination of the d_yz band and the topological surface state band in the superconducting state. These results reveal the origin of the flat band-like feature and rule out the presence of BCS-BEC crossover in Fe(Se,Te) superconductor.

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来源期刊

Chinese Physics B 物理-物理：综合

CiteScore

2.80

自引率

23.50%

发文量

15667

审稿时长

2.4 months

期刊介绍： Chinese Physics B is an international journal covering the latest developments and achievements in all branches of physics worldwide (with the exception of nuclear physics and physics of elementary particles and fields, which is covered by Chinese Physics C). It publishes original research papers and rapid communications reflecting creative and innovative achievements across the field of physics, as well as review articles covering important accomplishments in the frontiers of physics. Subject coverage includes: Condensed matter physics and the physics of materials Atomic, molecular and optical physics Statistical, nonlinear and soft matter physics Plasma physics Interdisciplinary physics.