High-Energy Magnetic Excitations from Heavy Quasiparticles in CeCu2Si2

Published

June 18, 2021

Author(s)

Yu Song, Weiyi Wang, Chongde Cao, Zahra Yamani, Yuanji Xu, Yutao Sheng, Wolfgang Loser, Yiming Qiu, Yi-Feng Yang, Robert J. Birgeneau, Pengcheng Dai

Abstract

The heavy fermion superconductor CeCu₂Si₂ is located near an antiferromagnetic quantum critical point, indicating significant interplay between magnetism and superconductivity. Using inelastic neutron scattering, we show magnetic excitations in CeCu₂Si₂ exhibit a strongly asymmetric dispersion for E approximatley less than or equal to} 1:5 meV, and at higher energies evolve into broad columnar magnetic excitations that extend to E approximatley greater than or equal to} 5 meV. While low-energy magnetic excitations exhibit marked three-dimensional characteristics, the high-energy magnetic excitations in CeCu₂Si₂ are almost two-dimensional, reminiscent of paramagnons found in cuprate and iron-based superconductors. By comparing our experimental findings with calculations in the random-phase approximation, we conclude that the magnetic excitations in CeCu₂Si₂ are well-described by intraband scattering of quasiparticles associated with its heavy electron band, which exhibits a relatively more prominent band renormalization. Our results provide a basis for understanding magnetism and superconductivity in CeCu₂Si₂, and demonstrate the utility of neutron scattering in probing renormalization with band-specificity in heavy fermion metals.

Citation

NPJ Quantum Materials

Volume

6

Issue

1

Pub Type

Journals

Keywords

heavy fermion supercondcutor, neutron scattering

Citation

Song, Y. , Wang, W. , Cao, C. , Yamani, Z. , Xu, Y. , Sheng, Y. , Loser, W. , Qiu, Y. , Yang, Y. , Birgeneau, R. and Dai, P. (2021), High-Energy Magnetic Excitations from Heavy Quasiparticles in CeCu₂Si₂, NPJ Quantum Materials (Accessed October 9, 2025)