Temperature-evolution of spectral function and optical conductivity in heavy fermion compound Ce2_{2}IrIn8_{8} under crystalline electric field

We investigate the role of the crystalline electric field (CEF) in the temperature ($T$)-evolution of the Kondo resonance states and its effect on optical conductivity. We perform the combined first principles calculation of the density functional theory and dynamical mean field theory on Ce$_{2}$IrIn$_{8}$. The calculated spectral function reproduces the experimental observed CEF states at low $T$, while it shows a drastic change of the Fermi surface upon increasing $T$. The effect of the CEF states on the Fermi surface as a function of $T$ is elucidated through the first principles calculations as well as the analysis on the Anderson impurity model. Consequently, we suggest the importance of the CEF-driven orbital anisotropy in the low-energy states of optical experiments.Comment: 6 pages, 4 figure

Composition and temperature dependent electronic structures of NiS2-xSex alloys: First-principles dynamical mean-field theory approach

We investigate the evolution of the electronic structure of NiS2-xSex alloys with varying temperature and composition x by using the combined approach of density-functional theory and dynamical mean-field theory. Adopting realistic alloy structures containing S and Se dimers, we map their electronic correlation strength on the phase diagram and observe the metal-insulator transition (MIT) at the composition x = 0.5, which is consistent with the experimental measurements. The temperature dependence of the local magnetic susceptibility is found to show a typical Curie-Weiss-like behavior in the insulating phase while it shows a constant Pauli-like behavior in the metallic phase. A comparison of the electronic structures for NiS2 and NiSe2 in different lattice structures suggests that the MIT in this alloy system can be classified as of bandwidth-control type, where the change in the hybridization strength between Ni d and chalcogen p orbitals is the most important parameter.113Nsciescopu

Scaling of the Anderson Lattice Model Studied by DMFT with CTQMC Impurity Solver

The Kondo lattice model is known to be the minimal model for the heavy fermi liquid state of the heavy fermion systems. In spite of its fermi-liquid-like behaviour - T2 resistivity, T-linear specific heat, and T-independent spin susceptibility - its nature including the scaling relation of various physical quantities has not fully unveiled yet [1]. It is due to the fact that an analytic methodology based on the mean-field theory is limited to describe finitetemperature properties such as very incoherent spectrum near the Fermi level, and there is no concrete methodology for describing the strong coupling nature of the heavy fermion systems. On the other hand, DMFT is one of the most promising candidate for describing the strongly correlated system in a non-perturbative manner [2]. Using DMFT with numerically exact CTQMC impurity solver, we may perform a very well-controlled experiment on ideal model systems. In this work, we studied the Kondo lattice model by the dynamical mean-field theory (DMFT) with continuous time quantum Monte-Carlo (CTQMC) impurity solver [3]. As a result, we observed the scaling of various physical quantities such as the local spin susceptibility and scattering rate of the Kondo lattice model with different hybridisation strength and temperature. Compared with the Kondo impurity model, Kondo lattice shows different scaling energy scale due to the feedback effect of the DMFT. Additionally, temperature evolutions of the spectral properties such as the Fermi surface and band structure at the characteristic energy scale will be given. Discussion on how the feedback effect may change the RG beta function will be also given.1

Orbital anisotropy of heavy fermion Ce2IrIn8 under crystalline electric field and its energy scale

© 2022 American Physical Society.We investigate the temperature (T) evolution of orbital anisotropy and its effect on spectral function and optical conductivity in Ce2IrIn8 using a first-principles dynamical mean-field theory combined with density functional theory. The orbital anisotropy develops by lowering T and it is intensified below a temperature corresponding to the crystalline-electric field (CEF) splitting size. Interestingly, the depopulation of CEF excited states leaves a spectroscopic signature, "shoulder,"in the T-dependent spectral function at the Fermi level. From the two-orbital Anderson impurity model, we demonstrate that CEF splitting size is the key ingredient influencing the emergence and the position of the "shoulder."Besides the two conventional temperature scales TK and T∗, we introduce an additional temperature scale to deal with the orbital anisotropy in heavy fermion systems.11Nsciescopu