Title: Pseudogap and pairing: shot noise reveals the pseudogap as pairing energy in a cuprate superconductor

Speaker: Jiasen Niu

Inviter: Hailong Fu

Time: 13:30pm, January 9（Friday）

Location: Room 322, No. 8 Hainayuan Building, Zijingang

Abstract：

In the cuprate high-temperature superconductors, the pseudogap phase connects the Mott insulator and superconductivity phases. Despite extensive research, the origin of the pseudogap remains elusive. A key question, debated for decades, is whether the pseudogap is associated with electron pairing, or if it corresponds to a local ordered state. Shot noise experiments, which can directly detect electron pairing, have the potential to resolve this long-standing debate [1].

In this talk, I will present unambiguous evidence supporting the pairing scenario using local shot-noise spectroscopy measurements in Bi2Sr2CaCuO8+δ [2]. Our finding excludes the possibility of the pseudogap arising solely from local orders, and instead indicates a clear relation between the pseudogap energy and Cooper pair formation. Finally, I will briefly discuss how the same noise-based approach can be extended to probe atomic-scale charge dynamics, which are invisible to conventional spectroscopy.

[1] J. Niu, et. al., Phys. Rev. Lett. 132, 076001 (2024).

[2] J. Niu, M. Larrazabal, et. al., arXiv: 2409.15928.

Bio：

Dr. Jiasen Niu received his PhD from Peking University in 2020 under the supervision of Prof. Xi Lin. He then began his postdoctoral research at Leiden University under the supervision of Milan Allan. In 2024, he continued his research with Prof. Allan at Ludwig Maximilian University of Munich, while also taking on the role of sub-group leader for the Leiden branch of the Allan group.

Dr. Niu’s research focuses on investigating electron correlations and microscopic dynamics in high-temperature superconductors using shot noise based techniques. He is particularly interested in developing and applying unconventional noise spectroscopy methods to uncover quantum phenomena that are inaccessible to conventional measurements.