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High-Energy Magnetic Excitations from Heavy Quasiparticles in CeCu2Si2



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


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.
NPJ Quantum Materials


heavy fermion supercondcutor, neutron scattering


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 CeCu<sub>2</sub>Si<sub>2</sub>, NPJ Quantum Materials (Accessed December 6, 2023)
Created June 17, 2021, Updated September 7, 2021