pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2020; 70: 637-645

Published online August 31, 2020 https://doi.org/10.3938/NPSM.70.637

## Study of the Electronic Structure for Ce(Fe$_{0.4}$Co$_{0.6}$)$_2$ and CeCo$_2$ Compounds

En-Jin CHO*1, Byung-Hee choi2, Jai-Kwan JUNG2, Ran-Ju JUNG2, Je-Geun park2, Takayuki MURO3, Shigemasa SUGA4

1Department of Physics, Chonnam National University, Gwangju 61186, Korea

2Department of Physics, Seoul National University, Seoul 08826, Korea
3Japan Synchrotron Radiation Research Institute, Sayogun, Hyogo 679-5198, Japan
4Department of Material Physics, Osaka University, Osaka 560-8531, Japan

Correspondence to:ejcho@chonnam.ac.kr

Received: April 19, 2020; Revised: June 17, 2020; Accepted: July 5, 2020

### Abstract

For Ce(Fe$_{0.4}$Co$_{0.6}$)$_{2}$ and CeFe$_{2}$ compounds, we obtained Fe/Co $3d$ and Ce $4f$ spectra by using photoelectron spectroscopy. With the Anderson impurity Hamiltonian, we analyzed theoretically the Ce $4f$ spectra of two compounds. Not only a bulk contribution but also a surface contribution to the Ce $4f$ spectrum is needed to explain the experimental Ce $4f$ spectrum, For the Ce(Fe$_{0.4}$Co$_{0.6}$)$_{2}$ compound, we obtained a theoretical bulk $4f$ spectrum by using a bare $f$ electron binding energy, $\epsilon_{f}^ B$, to be 0.90 eV and the average hybridization between a $f$ and conduction electrons, $\Delta_{av}^B$, to be 47.6 meV. From the theoretical results of the Ce(Fe$_{0.4}$Co$_{0.6}$)$_{2}$ compound, the number of $4f$ electrons, $n_{f}^B$, is 0.88 and the Kondo temperature, $T_{K}$, is 261K. For the CeCo$_{2}$ compound, we obtained a theoretical bulk $4f$ spectrum, $n_{f}^B$=0.80 and $T_{K}$=691K with $\epsilon_{f}^ B$=0.90 eV and $\Delta_{av}^B$=61.5 meV.

Keywords: Resonant Photoemission Spectroscopy, Electronic Structure