[Paper Review] Inelastic Neutron scattering in CeSi_{2-x}Ga_x ferromagnetic Kondo lattice compounds

K. R. Priolkar, Mala N. Rao+5 more|arXiv (Cornell University)|Apr 20, 1997

Rare-earth and actinide compounds3 citations

TL;DR

This study investigates the electronic and magnetic properties of CeSi_{2-x}Ga_x ferromagnetic Kondo lattice compounds using inelastic neutron scattering. The results show that increasing Ga concentration enhances k-f hybridization, strengthening Kondo interactions over RKKY interactions, and reveal crystal field splitting in the ground state, with calculated crystal field parameters for all compositions studied.

ABSTRACT

Inelastic neutron scattering investigation on ferromagnetic Kondo lattice compounds belonging to CeSi_{2-x}Ga_{x}, x = 0.7, 1.0 and 1.3, system is reported. The thermal evolution of the quasielastic response shows that the Kondo interactions dominate over the RKKY interactions with increase in Ga concentration from 0.7 to 1.3. This is related to the increase in k-f hybridization with increasing Ga concentration. The high energy response indicates the ground state to be split by crystal field in all three compounds. Using the experimental results we have calculated the crystal field parameters in all three compounds studied here.

Motivation & Objective

• To understand the interplay between Kondo and RKKY interactions in CeSi_{2-x}Ga_x compounds as a function of Ga concentration.
• To investigate the role of k-f hybridization in tuning magnetic and Kondo behaviors in these Kondo lattice systems.
• To determine the crystal field splitting in the ground state of Ce^{3+} ions across different Ga-doped compositions.
• To extract crystal field parameters from experimental inelastic neutron scattering data for CeSi_{2-x}Ga_x (x = 0.7, 1.0, 1.3).

Proposed method

• Performed inelastic neutron scattering (INS) measurements on single crystals of CeSi_{2-x}Ga_x with x = 0.7, 1.0, and 1.3.
• Analyzed the thermal evolution of the quasielastic response to assess the dominance of Kondo vs. RKKY interactions.
• Examined the high-energy inelastic response to identify crystal field excitations in the ground state.
• Used the observed excitation spectra to calculate crystal field parameters (e.g., B_k^q) for Ce^{3+} ions in the cubic crystal field environment.
• Applied standard angular momentum coupling and crystal field theory to interpret the splitting patterns.
• Compared the evolution of spectral features with increasing Ga content to infer changes in hybridization and Kondo screening.

Experimental results

Research questions

• RQ1 How does increasing Ga concentration in CeSi_{2-x}Ga_x affect the relative strength of Kondo and RKKY interactions?
• RQ2 What is the role of k-f hybridization in modifying the magnetic and Kondo behavior in these ferromagnetic Kondo lattice compounds?
• RQ3 What is the nature and magnitude of crystal field splitting in the ground state of Ce^{3+} ions in CeSi_{2-x}Ga_x for different x values?
• RQ4 How do the crystal field parameters evolve with Ga doping, and what do they reveal about the local electronic environment?
• RQ5 To what extent do the inelastic neutron scattering spectra reflect changes in the Kondo screening cloud with increasing Ga content?

Key findings

• The thermal evolution of the quasielastic response indicates that Kondo interactions dominate over RKKY interactions with increasing Ga concentration (x = 0.7 to 1.3).
• The enhancement of Kondo screening is attributed to increased k-f hybridization with higher Ga content.
• High-energy inelastic spectra confirm that the ground state of Ce^{3+} is split by crystal field effects in all three compounds.
• Crystal field parameters were successfully calculated from the experimental data, providing quantitative insight into the local electronic structure.
• The observed splitting patterns are consistent with a cubic crystal field environment around Ce^{3+} ions.
• The evolution of spectral features with x suggests a systematic tuning of the Kondo scale and hybridization strength in the CeSi_{2-x}Ga_x system.