Anisotropic c − f Hybridization in the Ferromagnetic Quantum Critical Metal CeRh6Ge4

Yi Wu, Yongjun Zhang, Feng Du, Bin Shen, Hao Zheng, Yuan Fang, Michael Smidman, Chao Cao, Frank Steglich, Huiqiu Yuan, Jonathan D. Denlinger, and Yang Liu

Heavy fermion compounds exhibiting a ferromagnetic quantum critical point have attracted considerable interest. Common to two known cases, i.e., ${\mathrm{CeRh}}_6{\mathrm{Ge}}_4$ and ${\mathrm{YbNi}}_4{P}_2$, is that the $4f$ moments reside along chains with a large interchain distance, exhibiting strong magnetic anisotropy that was proposed to be vital for the ferromagnetic quantum criticality. Here, we report an angle-resolved photoemission study on ${\mathrm{CeRh}}_6{\mathrm{Ge}}_4$ in which we observe sharp momentum-dependent $4f$ bands and clear bending of the conduction bands near the Fermi level, indicating considerable hybridization between conduction and $4f$ electrons. The extracted hybridization strength is anisotropic in momentum space and is obviously stronger along the Ce chain direction.The hybridized $4f$ bands persist up to high temperatures, and the evolution of their intensity shows clear band dependence. Our results provide spectroscopic evidence for anisotropic hybridization between conduction and $4f$ electrons in ${\mathrm{CeRh}}_6{\mathrm{Ge}}_4$, which could be important for understanding the electronic origin of the ferromagnetic quantum criticality.

Phys. Rev. Lett. 126, 216406

The published article is available at https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.216406