Yiming Sun, Yubing Tu, Yang Luo, Shuikang Yu, Hongyu Li, Yunmei Zhang, Ping Wu, Zhuying Wang, Fan Zhang, Wanru Ma, Zuowei Liang, Jianjun Ying, Tao Wu, Ziji Xiang, Junfeng He, Lei Shan, Zhenyu Wang, Xianhui Chen
{"title":"成像动量空间库珀对的形成及其与可果美超导体中电荷密度波隙的竞争","authors":"Yiming Sun, Yubing Tu, Yang Luo, Shuikang Yu, Hongyu Li, Yunmei Zhang, Ping Wu, Zhuying Wang, Fan Zhang, Wanru Ma, Zuowei Liang, Jianjun Ying, Tao Wu, Ziji Xiang, Junfeng He, Lei Shan, Zhenyu Wang, Xianhui Chen","doi":"10.1007/s11433-023-2360-y","DOIUrl":null,"url":null,"abstract":"<p>The superconducting ground state of kagome metals <i>A</i>V<sub>3</sub>Sb<sub>5</sub> (where <i>A</i> stands for K, Rb, or Cs) emerges from an exotic charge density wave (CDW) state that potentially breaks both rotational and time reversal symmetries. However, the specifics of the Cooper pairing mechanism, and the nature of the interplay between these two states remain elusive, largely due to the lack of momentum-space (<i>k</i>-space) superconducting energy gap structure. By implementing Bogoliubov quasiparticle interference (BQPI) imaging, we obtain <i>k</i>-space information on the multiband superconducting gap structure Δ<span>\n<sup><i>i</i></sup><sub>SC</sub>\n</span>(<i>k</i>) in pristine CsV<sub>3</sub>Sb<sub>5</sub>. We show that the estimated energy gap on the vanadium <span>\\({d_{x{y \\mathord{\\left/ {\\vphantom {y {{x^{\\rm{2}}} - {y^{\\rm{2}}}}}} \\right.} {{x^{\\rm{2}}} - {y^{\\rm{2}}}}}}}\\)</span> orbital is anisotropic but nodeless, with a minimal value located near the M point. Interestingly, a comparison of Δ<span>\n<sup>i</sup><sub>SC</sub>\n</span>(<i>k</i>) with the CDW gap Δ<span>\n<sup><i>i</i></sup><sub>CDW</sub>\n</span>(<i>k</i>) obtained by angle-resolved photoemission spectroscopy (ARPES) reveals direct <i>k</i>-space competition between these two order parameters, i.e., the opening of a large (small) CDW gap at a given momentum corresponds to a small (large) superconducting gap. When the long-range CDW order is suppressed by replacing vanadium with titanium, we find a nearly isotropic energy gap on both the V and Sb bands. This information will be critical for identifying the microscopic pairing mechanism and its interplay with intertwined electronic orders in this kagome superconductor family.</p>","PeriodicalId":774,"journal":{"name":"Science China Physics, Mechanics & Astronomy","volume":null,"pages":null},"PeriodicalIF":6.4000,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Imaging momentum-space Cooper pair formation and its competition with the charge density wave gap in a kagome superconductor\",\"authors\":\"Yiming Sun, Yubing Tu, Yang Luo, Shuikang Yu, Hongyu Li, Yunmei Zhang, Ping Wu, Zhuying Wang, Fan Zhang, Wanru Ma, Zuowei Liang, Jianjun Ying, Tao Wu, Ziji Xiang, Junfeng He, Lei Shan, Zhenyu Wang, Xianhui Chen\",\"doi\":\"10.1007/s11433-023-2360-y\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>The superconducting ground state of kagome metals <i>A</i>V<sub>3</sub>Sb<sub>5</sub> (where <i>A</i> stands for K, Rb, or Cs) emerges from an exotic charge density wave (CDW) state that potentially breaks both rotational and time reversal symmetries. However, the specifics of the Cooper pairing mechanism, and the nature of the interplay between these two states remain elusive, largely due to the lack of momentum-space (<i>k</i>-space) superconducting energy gap structure. By implementing Bogoliubov quasiparticle interference (BQPI) imaging, we obtain <i>k</i>-space information on the multiband superconducting gap structure Δ<span>\\n<sup><i>i</i></sup><sub>SC</sub>\\n</span>(<i>k</i>) in pristine CsV<sub>3</sub>Sb<sub>5</sub>. We show that the estimated energy gap on the vanadium <span>\\\\({d_{x{y \\\\mathord{\\\\left/ {\\\\vphantom {y {{x^{\\\\rm{2}}} - {y^{\\\\rm{2}}}}}} \\\\right.} {{x^{\\\\rm{2}}} - {y^{\\\\rm{2}}}}}}}\\\\)</span> orbital is anisotropic but nodeless, with a minimal value located near the M point. Interestingly, a comparison of Δ<span>\\n<sup>i</sup><sub>SC</sub>\\n</span>(<i>k</i>) with the CDW gap Δ<span>\\n<sup><i>i</i></sup><sub>CDW</sub>\\n</span>(<i>k</i>) obtained by angle-resolved photoemission spectroscopy (ARPES) reveals direct <i>k</i>-space competition between these two order parameters, i.e., the opening of a large (small) CDW gap at a given momentum corresponds to a small (large) superconducting gap. When the long-range CDW order is suppressed by replacing vanadium with titanium, we find a nearly isotropic energy gap on both the V and Sb bands. 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引用次数: 0
摘要
神户金属 AV3Sb5(其中 A 代表 K、Rb 或 Cs)的超导基态来自一种奇特的电荷密度波(CDW)态,它可能打破旋转对称性和时间反转对称性。然而,库珀配对机制的具体细节以及这两种状态之间相互作用的性质仍然难以捉摸,这主要是由于缺乏动量空间(k-space)超导能隙结构。通过实施波哥留布夫准粒子干涉(BQPI)成像,我们获得了原始 CsV3Sb5 中多带超导能隙结构 ΔiSC(k) 的 k 空间信息。我们表明,钒上的估计能隙({d_{x{y \mathord\{left/ {\vphantom {y {{x^{\rm{2}}}- {y^{\rm{2}}}}}}\right.}{{x^{\rm{2}} {y^{\rm{2 (right.}- {y^{/rm{2}}}}}}})轨道是各向异性的,但没有节点,其最小值位于 M 点附近。有趣的是,将ΔiSC(k)与角分辨光发射光谱(ARPES)获得的CDW间隙ΔiCDW(k)进行比较,可以发现这两个阶次参数之间存在直接的k空间竞争关系,即在给定动量下,大(小)CDW间隙的打开与小(大)超导间隙相对应。当用钛代替钒来抑制长程 CDW 有序时,我们发现在 V 带和 Sb 带上都存在近乎各向同性的能隙。这些信息对于确定微观配对机制及其与这个可果美的超导体家族中相互交织的电子阶的相互作用至关重要。
Imaging momentum-space Cooper pair formation and its competition with the charge density wave gap in a kagome superconductor
The superconducting ground state of kagome metals AV3Sb5 (where A stands for K, Rb, or Cs) emerges from an exotic charge density wave (CDW) state that potentially breaks both rotational and time reversal symmetries. However, the specifics of the Cooper pairing mechanism, and the nature of the interplay between these two states remain elusive, largely due to the lack of momentum-space (k-space) superconducting energy gap structure. By implementing Bogoliubov quasiparticle interference (BQPI) imaging, we obtain k-space information on the multiband superconducting gap structure ΔiSC(k) in pristine CsV3Sb5. We show that the estimated energy gap on the vanadium \({d_{x{y \mathord{\left/ {\vphantom {y {{x^{\rm{2}}} - {y^{\rm{2}}}}}} \right.} {{x^{\rm{2}}} - {y^{\rm{2}}}}}}}\) orbital is anisotropic but nodeless, with a minimal value located near the M point. Interestingly, a comparison of ΔiSC(k) with the CDW gap ΔiCDW(k) obtained by angle-resolved photoemission spectroscopy (ARPES) reveals direct k-space competition between these two order parameters, i.e., the opening of a large (small) CDW gap at a given momentum corresponds to a small (large) superconducting gap. When the long-range CDW order is suppressed by replacing vanadium with titanium, we find a nearly isotropic energy gap on both the V and Sb bands. This information will be critical for identifying the microscopic pairing mechanism and its interplay with intertwined electronic orders in this kagome superconductor family.
期刊介绍:
Science China Physics, Mechanics & Astronomy, an academic journal cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China, and published by Science China Press, is committed to publishing high-quality, original results in both basic and applied research.
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