scholarly journals Many-body effects on the resistivity of a multi-orbital system beyond Landau's Fermi-liquid theory

2015 ◽  
Vol 29 (15) ◽  
pp. 1530005 ◽  
Author(s):  
Naoya Arakawa
Keyword(s):  
Temperature Dependence ◽  
Fermi Liquid ◽  
Quantum Critical Point ◽  
Electron Systems ◽  
Many Body ◽  
Correlated Electron Systems ◽  
Orbital System ◽  
Self Energy ◽  
Correlated Electron ◽  
Many Body Effects

I review many-body effects on the resistivity of a multi-orbital system beyond Landau's Fermi-liquid (FL) theory. Landau's FL theory succeeds in describing electronic properties of some correlated electron systems at low temperatures. However, the behaviors deviating from the temperature dependence in the FL, non-FL-like behaviors, emerge near a magnetic quantum-critical point (QCP). These indicate the importance of many-body effects beyond Landau's FL theory. Those effects in multi-orbital systems have been little understood, although their understanding is important to deduce ubiquitous properties of correlated electron systems and characteristic properties of multi-orbital systems. To improve this situation, I formulate the resistivity of a multi-orbital Hubbard model using the extended Éliashberg theory and adopt this method to the inplane resistivity of quasi-two-dimensional paramagnetic ruthenates in combination with the fluctuation-exchange approximation including the current vertex corrections arising from the self-energy and Maki–Thompson term. The results away from and near the antiferromagnetic QCP reproduce the temperature dependence observed in Sr 2 RuO 4 and Sr 2 Ru 0.075 Ti 0.025 O 4, respectively. I highlight the importance of not only the momentum and the temperature dependence of the damping of a quasiparticle but also its orbital dependence in discussing the resistivity of correlated electron systems.

NOVEL MANY-BODY EFFECTS IN PHOTOEMISSION AND INVERSE PHOTOEMISSION SPECTRA OF ULTRATHIN TRANSITION-METAL FILMS

1991 ◽  
Vol 05 (08) ◽  
pp. 1147-1178 ◽  
Author(s):  
CHANGFENG CHEN
Keyword(s):  
Transition Metal ◽  
Local Density ◽  
Many Body ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Nickel Iron ◽  
Correlated Electron ◽  
Inverse Photoemission ◽  
Recent Developments ◽  
Many Body Effects

We present an overview of some recent developments in the theoretical modeling of transition-metal systems, particularly the ultrathin-film structures, focusing on the effects of electron-electron interactions. We describe the progress in the understanding of how to model realistic strongly correlated electron systems using and going beyond the local-density-approximation single-particle electronic structures. Results of exact many-body calculations of photoemission and inverse photoemission spectra of ultrathin nickel, iron and cobalt films are shown to illustrate the application of our approach. Interesting new features induced by many-body effects are found and discussed. Comparison with available experimental results is presented and further work, both experimental and theoretical, is suggested.

scholarly journals PHENOMENOLOGICAL MODELING OF PHOTOEMISSION SPECTRA IN STRONGLY CORRELATED ELECTRON SYSTEMS

2002 ◽  
Vol 16 (25) ◽  
pp. 3759-3770 ◽  
Author(s):  
KRZYSZTOF BYCZUK ◽  
RALF BULLA ◽  
RALPH CLAESSEN ◽  
DIETER VOLLHARDT
Keyword(s):  
Analytical Formula ◽  
Phenomenological Approach ◽  
Spectral Weight ◽  
Strongly Correlated Electron Systems ◽  
Strongly Correlated ◽  
Electron Systems ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Self Energy ◽  
Correlated Electron

A phenomenological approach is presented that allows one to model, and thereby interpret photoemission spectra of strongly correlated electron systems. A simple analytical formula for the self-energy is proposed. This self-energy describes both the coherent and incoherent parts of the spectrum (quasiparticle and Hubbard peaks, respectively). Free parameters in the expression are determined by fitting the density of states to experimental photoemission data. An explicit fitting is presented for the La 1-x Sr x TiO 3 system with 0.08 ≤ x ≤ 0.38. In general, our phenomenological approach provides information on the effective mass, the Hubbard interaction, and the spectral weight distribution in different parts of the spectrum. Limitations of this approach are also discussed.

scholarly journals QUASIPARTICLE MANY-BODY DYNAMICS OF THE ANDERSON MODEL

1996 ◽  
Vol 10 (15) ◽  
pp. 1895-1912 ◽  
Author(s):  
A.L. KUZEMSKY
Keyword(s):  
General Scheme ◽  
Coulomb Repulsion ◽  
Dyson Equation ◽  
Many Body ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Self Energy ◽  
Correlated Electron ◽  
The Many ◽  
The One

The paper addresses the many-body quasiparticle dynamics of the Anderson impurity model at finite temperatures in the framework of the equation-of-motion method. We find a new exact identity relating the one-particle and many-particle Green’s functions. Using this identity we present a consistent and general scheme for a construction of generalized mean fields (elastic scattering corrections) and self-energy (inelastic scattering) in terms of Dyson equation. A new approach for the complex expansion for the single-particle propagator in terms of Coulomb repulsion U and hybridization V is proposed. Using the exact identity, the essentially new many-body dynamical solution of SIAM has been derived. This approach offers a new way for the systematic construction of the approximative interpolating dynamical solutions of the strongly correlated electron systems.

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