籠目結構超導體CsV₃Sb₅中的競爭電子序和拓撲

時間👨🏽‍✈️：2022年6月10日（星期五）15:00—16:00

主講人🏒：陳仙輝院士 中國科學技術大學

主持人👩‍⚖️：王楠林 nlwang@pku.edu.cn

報告人簡介👩🏻‍🎤：

陳仙輝🤛🏻，中國科學技術大學教授👳🏽，中國科學院強耦合量子材料物理重點實驗室主任。1992年在中國科學技術大學物理系獲理學博士學位，曾先後作為洪堡基金學者在德國卡爾斯魯厄研究中心和斯圖加特馬克斯·普朗克固體物理研究所工作👨‍👧‍👦，作為訪問學者在日本北陸先端科學技術研究院🍠、美國休斯敦大學德克薩斯超導研究中心和新加坡國立大學工作🧘🏽。陳仙輝長期從事超導和量子材料的探索及其物理研究🐕，迄今已在《自然》（Nature）、《科學》（Science）等刊物發表SCI論文460余篇🐯。曾獲長江學者成就獎（2008）、求是傑出科技成就集體獎（2009）、國家自然科學獎一等獎（2013）🔳、國際超導材料最高獎馬蒂亞斯獎（Bernd T. Matthias Prize）（2015）🕕、何梁何利基金科學與技術進步獎（2017）、發展中國家科學院（TWAS）物理學獎（2020）等。1998年獲國家傑出青年科學基金資助🤵🏻‍♂️，2002年入選教育部“長江學者獎勵計劃”特聘教授，2015年當選中國科學院院士。

報告摘要:

Kagome compounds provide a fertile playground to explore the rich interplay between geometry, topology and electronic correlations. In this talk, we focus on a topological kagome metal CsV3Sb5which exhibits cascade of symmetry-breaking electronic phases, including charge density wave, electronic nematicity and superconductivity. A giant anomalous Hall conductivity is observed exactly following the CDW transition, and the superconductivity shows an unusual competition with this CDW state under pressure. These findings point to an unconventional nature of the CDW. Deeply in the CDW state, we found the emergence of electronic nematicity that intertwines with CDW and superconductivity, drawing strike parallel to the high temperature superconductors. A new CDW phase induced by pressure, evolving from the electronic nematicity in ambient-pressure triple-Q CDW state, is observed between Pc1 ~ 0.76 GPa and Pc2 ~ 2.02 GPa for the first time. Such new CDW, ascribed to a possible stripe-like CDW order with a unidirectional 4a0 modulation, is likely to intertwine with superconductivity and leads to the two-dome feature of the superconducting phase. Meantime, we perform soft point-contact spectroscopy (SPCS) measurements in CsV3Sb5 to investigate the evolution of superconducting order parameter with pressure. Surprisingly, we find that the superconducting gap is significantly enhanced between the two SC domes. Moreover, the temperature dependence of the SC gap in this pressure range severely deviates from the conventional BCS behavior, evidencing for strong Cooper pair phase fluctuations. At low temperatures, the topological surface states cooperate with superconductivity, and Majorana zero modes can be realized inside the vortex cores. These findings reveal the complex intertwining of the stripe-like CDW with SC in the compressed CsV3Sb5, suggesting striking parallel to the cupratesuperconductor La2-xBaxCuO4. Our results point to the essential role of charge degree of freedom in the development of intertwining electronic orders, thus provides new constraints for theories.All these results establish CsV3Sb5 as an ideal playground to study the topology and correlation driven exotic electronic orders.

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