Evolution of the Kondo resonance feature and its relationship to spin-orbit coupling across the quantum critical point in Ce ₂ Rh _1−x Co _x Si ₃

Abstract

We investigate the evolution of the electronic structure of Ce2Rh1−xCoxSi3 as a function of x employing high resolution photoemission spectroscopy. Co substitution at the Rh sites in antiferromagnetic Ce2RhSi3 leads to a transition from an antiferromagnetic system to a Kondo system, Ce2CoSi3 via the Quantum Critical Point (QCP). High resolution photoemission spectra reveal distinct signature of the Kondo resonance feature (KRF) and its spin orbit split component (SOC) in the whole composition range indicating finite Kondo temperature scale at the quantum critical point. We observe that the intensity ratio of the Kondo resonance feature and its spin orbit split component, KRF/SOC gradually increases with the decrease in temperature in the strong hybridization limit. The scenario gets reversed if the Kondo temperature becomes lower than the magnetic ordering temperature. While finite Kondo temperature within the magnetically ordered phase indicates applicability of the spin density wave picture at the approach to QCP, the dominant temperature dependence of the spin-orbit coupled feature suggests importance of spin-orbit interactions in this regime.

Valence Band of Ce_2Co_{0.8}Si_{3.2} and Ce_2RhSi_3 Studied by Resonant Photoemission Spectroscopy and FPLO Calculations

“…The Kondo peak intensity is clearly higher for Ce 2 Co 0.8 Si 3.2 , in line with stronger hybridization in this compound. This agrees with the previous PES studies [9]. The o-resonance spectra are dominated by 3d electrons from Co and Rh.…”

“…indicated the presence of a Kondo resonance in antiferromagnetic Ce 2 RhSi 3 [7] and paramagnetic Ce 2 CoSi 3 [8]. It appears that the Kondo resonance has higher intensity for Ce 2 CoSi 3 when compared to Ce 2 RhSi 3 system with coexisting magnetic order and Kondo interaction [9]. Recently, a momentum dependence of the Kondo peak was established in Ce 2 Co 0.8 Si 3.2 by means of angle-resolved photoemission spectroscopy (ARPES) [10].…”

Three-dimensional bulk electronic structure of the Kondo lattice CeIn3 revealed by photoemission

“…Polycrystal photoemission measurements 22 , angular correlation of the electron-positron annihilation radiation 23 , and de Haas-van Alphen (dHvA) 24 measurements all reveal the localized nature of f electrons at ambient pressure. Photoemission spectroscopy is a powerful tool to detect the reconstruction of the electronic structure and is often used to judge the nature of f electrons 25 26 27 28 . Photoemission spectroscopy can even be used to detect the SC energy gap in HF systems 29 .…”

Site‐dependent correlation strength and occupation number of 5f electrons in alpha phase plutonium metal

“…In fact, besides the 5f-5f on-site Coulomb interaction and the Kondo effect [19,78], the dual characteristics of 5f electrons locating at the boundary between the itinerant and localized regimes results in interplay of SOC splitting, crystal field interaction and Hund's interaction [19,79]. In principle, these 5f-derived spectra characters could be utilized to estimate the Kondo resonance feature [80].…”