Interplay of Kondo Physics with Incommensurate Charge Density Waves in CeTe$_3$

TL;DR

This study investigates how incommensurate charge density waves interact with Kondo physics in CeTe$_3$, revealing momentum-dependent hybridization effects that influence effective masses but do not produce heavy fermions.

Contribution

It provides the first detailed ARPES analysis of the hybridization between localized 4f states and itinerant electrons in CeTe$_3$, highlighting momentum-dependent effects.

Findings

Hybridization with localized 4f states is momentum-dependent and extends to the Fermi level.

The hybridization affects effective masses marginally, not leading to heavy fermions.

The observed effects may explain discrepancies in heavy fermion mass measurements.

Abstract

CeTe$_3$ is a 2--dimensional (2D) Van der Waals (VdW) material with incommensurate charge density waves (CDW), extremely high transition temperature ($T_{CDW}$) and a large momentum--dependent CDW gap that leaves a significant portion of the Fermi surface intact. It is also considered to be a weak Kondo system, a property unexpected for a material with incommensurate CDW, where each atomic site is slightly different. Here, we study the properties of the CDW state in several RTe$_3$ (R is rare earth) materials and examine the hybridization of itinerant states with the localized Ce $4f$ multiplet in CeTe$_3$ by using angle resolved photoemission spectroscopy (ARPES). We find that the renormalization of the itinerant states originating from the hybridization with the deeper localized $4f$ states at $-260$ meV is $k-$dependent and extends to the Fermi level. As these localized states are far from the Fermi level, the observed hybridization affects the effective masses only marginally and does not lead to heavy fermions. However, since the same renormalizing mechanism normally leads to the heavy fermion physics when the localized $4f$ states are near the Fermi level, our observation of its strong $k-$dependence suggests that this could be the reason for discrepancy between the heavy masses in specific heat and light ones in Shubnikov de Haas oscillations, often observed in heavy fermions.