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开云官方入口: Pairing mechanism for the high-temperature superconductivity in La3Ni2O7 under pressure

发布时间:2024-07-09浏览次数:10

报告题目: Pairing mechanism for the high-temperature superconductivity in La3Ni2O7 under pressure

报告人:杨帆教授  北京理工大学

报告时间:2024.7.22 上午10:00

报告地点:物理科技楼155

报告邀请人:蒋密

报告摘要:The recently discovered high-temperature superconductivity in La3Ni2O7 under pressure has attracted a great deal of interests. In this talk, I will introduce our recent studies on this system from combined weak-coupling and strong-coupling viewpoints.  In the weak-coupling perspective, we adopted a random-phase-approximation (RPA) approach based study on the system. Our calculations reveal an s+- wave pairing symmetry driven by spin fluctuations. We further found the emergence of local moments in the vicinity of apical-oxygen deficiencies, which significantly suppresses the Tc. In the strong-coupling perspective, we built up a single dx2-y2-orbital bilayer t-J model, in which the two layers are coupled via the super-exchange interaction transferred from the dz2-orbital assisted by the Hund’s coupling. Our slave-boson-mean-field approach based study reveal that the effective interlayer super-exchange not only changes the pairing symmetry from d-wave to s-wave, but also strongly enhance the Tc. The connection between the two viewpoints is also discussed at the end.

报告人简介:杨帆是北京理工大学物理开云官方入口教授。2002年博士毕业于北京大学物理开云官方入口,2004年从清华大学高等研究中心博后出站,之后加入北京理工大学物理开云官方入口。2013年被聘为教授。获得教育部“新世纪优秀人才“称号。杨帆的主要研究方向为强关联和超导理论。集中关注各类强关联电子材料当中的非常规超导。在铜基超导、铁基超导、镍基超导、量子自旋液体、魔角石墨烯、准晶电子态等领域从事研究多年。发表论文70余篇,引用2500余次。

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