Spin pumping effect is a sensitive and well-established experimental method in two-dimensional (2D) magnetic materials. In this talk, we focus on the exotic case that strong interactions render Landau’s quasiparticle not well-defined and the correlated system near a quantum critical point becomes a non-Fermi liquid(NFL) metal. We study the spin pumping effect of the NFL metal where the spin angular moments are not carried by any quasiparticles. We propose that spin pumping effect can be a valuable probe for NFL behaviors at the 2D interface of magnetic heterostructures. We show that the conventional Gilbert damping mechanism becomes invalid in the low-temperature regime, where it exhibits a power-law divergent ferromagnetic resonance (FMR) modulation; Whereas, at finite temperatures, Gilbert damping is restored. In both regimes, the non-quasiparticle nature of the NFL metal can be extracted from experimentally measurable FMR modulation signals. If time allows, we will briefly mention our works on the NFL, including a novel type of NFL arises from a magnetic heterostructure, and more importantly, the strange metal transport that is relevant to the high-Tc cuprate superconductor and twisted bilayer graphene.

About the speaker:

Xiao-Tian Zhang (张啸天) earned his bachelor’s degree from the College for Gifted Youngs at the University of Science and Technology of China in 2013. He then pursued his PhD at the International Center for Quantum Materials, Peking University, under the supervision of Prof. Ryuichi Shindou, graduating in 2019. From 2019 to 2022, he worked as a postdoc in Prof. Gang Chen’s group at the University of Hong Kong. In 2022, he joined the Kavli Institute for Theoretical Sciences at UCAS, as a Director’s Postdoctoral Fellow and Special Research Assistant (a.k.a. Assistant Researcher).

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