Electronic structure and transport properties of CeNi9In2

TL;DR

This study explores the electronic structure and transport properties of CeNi9In2, revealing a Fermi liquid state at low temperatures, mainly Ce 4f states near the Fermi energy, and a hybridization close to 104 meV, with experimental and theoretical insights.

Contribution

It provides a comprehensive analysis combining resistivity measurements, photoemission spectroscopy, and theoretical calculations to characterize CeNi9In2 as a mixed valence system with specific electronic features.

Findings

Resistivity consistent with Fermi liquid behavior at low T

Ce 4f states mainly located near Fermi energy

Hybridization parameter approximately 104 meV

Abstract

We investigated CeNi9In2 compound, which has been considered as a mixed valence (MV) system. Electrical resistivity vs. temperature variation was analysed in terms of the model proposed by Freimuth for systems with unstable 4f shell. At low temperature the resistivity dependence is consistent with a Fermi liquid state with a contribution characteristic of electron-phonon interaction. Ultraviolet photoemission spectroscopy (UPS) studies of the valence band did not reveal a Kondo peak down to 14 K. A difference of the spectra obtained with photon energies of low and high photoionization cross sections for Ce 4f electrons indicated that 4f states are located mainly close to the Fermi energy. The peaks related to f_{5/2}^1 and f_{7/2}^1 final states cannot be resolved but form a plateau between -0.3 eV and the Fermi energy. X-ray photoemission spectroscopy (XPS) studies were realized for the cerium 3d level. The analysis of XPS spectra within the Gunnarsson-Sh\"onhammer theory yielded a hybridization parameter of 104 meV and non-integer f level occupation, being close to 3. Calculations of partial densities of states were realized by a full potential local orbital (FPLO) method. They confirm that the valence band is dominated by Ni 3d states and are in general agreement with the experiment except for the behavior of f-electrons.