Band Calculation for Ce-compounds on the basis of Dynamical Mean Field Theory

TL;DR

This paper develops a DMFT-based band calculation scheme for Ce compounds, accurately capturing Kondo physics, crystal field, and spin-orbit effects, and applies it to Ce metal and CeSb to reproduce experimental spectra and estimate Kondo temperatures.

Contribution

It introduces a novel NCAf^{2}v' method for impurity solving within DMFT, enabling quantitative calculations including crystal field and spin-orbit splitting effects.

Findings

Reproduces photo-emission spectra with spin-orbit side peaks.

Estimates Kondo temperatures of 70 K for γ-Ce and 1700 K for α-Ce.

Successfully models spectral features of CeSb.

Abstract

The band calculation scheme for $f$ electron compounds is developed on the basis of the dynamical mean field theory (DMFT) and the LMTO method. The auxiliary impurity problem is solved by a method named as NCA$f^{2}$v', which includes the correct exchange process of the $f^{1} \to f^{2}$ virtual excitation as the vertex correction to the non-crossing approximation (NCA) for the $f^{1} \to f^{0}$ fluctuation. This method leads to the correct magnitude of the Kondo temperature, $T_{\rm K}$, and makes it possible to carry out quantitative DMFT calculation including the crystalline field (CF) and the spin-orbit (SO) splitting of the self-energy. The magnetic excitation spectra are also calculated to estimate $T_{\rm K}$. It is applied to Ce metal and CeSb at T=300 K as the first step. In Ce metal, the hybridization intensity (HI) just below the Fermi energy is reduced in the DMFT band. The photo-emission spectra (PES) have a conspicuous SO side peak, similar to that of experiments. $T_{\rm K}$ is estimated to be about 70 K in $\gamma$-Ce, while to be about 1700 K in $\alpha$-Ce. In CeSb, the double-peak-like structure of PES is reproduced. In addition, $T_{\rm K}$ which is not so low is obtained because HI is enhanced just at the Fermi energy in the DMFT band.