Chen Q Y, Xu D F, Niu X H, Peng R, Xu H C, Wen C H P, Liu X, Shu L, Tan S Y, Lai X C, Zhang Y J, Lee H, Strocov V N, Bisti F, Dudin P, Zhu J-X, Yuan H Q, Kirchner S, Feng D L
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China.
Phys Rev Lett. 2018 Feb 9;120(6):066403. doi: 10.1103/PhysRevLett.120.066403.
A key issue in heavy fermion research is how subtle changes in the hybridization between the 4f (5f) and conduction electrons can result in fundamentally different ground states. CeRhIn_{5} stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn_{5}, we demonstrate that the use of resonant angle-resolved photoemission spectroscopy with polarized light allows us to extract detailed information on the 4f crystal field states and details on the 4f and conduction electron hybridization, which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f electrons and identify two of the three Ce 4f_{5/2}^{1} crystal-electric-field levels and band-dependent hybridization, which signals that the hybridization occurs primarily between the Ce 4f states in the CeIn_{3} layer and two more three-dimensional bands composed of the Rh 4d and In 5p orbitals in the RhIn_{2} layer. Our results allow us to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound.
重费米子研究中的一个关键问题是，4f（5f）电子与传导电子之间杂化的细微变化如何导致截然不同的基态。CeRhIn₅就是一个特别显著的例子：用Co或Ir取代Rh时，反铁磁性会被超导性取代。在这项对CeRhIn₅的光电子能谱研究中，我们证明，使用带偏振光的共振角分辨光电子能谱，能够让我们获取有关4f晶体场态的详细信息，以及4f与传导电子杂化的细节，这些共同决定了基态。我们直接观测到了f电子的弱色散近藤共振，并确定了三个Ce 4f₅/₂¹晶体电场能级中的两个以及与能带相关的杂化，这表明杂化主要发生在CeIn₃层中的Ce 4f态与RhIn₂层中由Rh 4d和In 5p轨道组成的另外两个三维能带之间。我们的结果使我们能够将在高温下观测到的性质与这种神秘的重费米子化合物不同寻常的低温性质联系起来。
