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森川良忠
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Title: Photoemission Spectra of Correlated Materials from
First-Principles Theory
Speaker: Professor Ferdi Aryasetiawan
Lund University, Mathematical Physics
Date & Time: July 25th , 2018, 16:00-17:00
Place: Osaka University Suita Campus, Graduate School of Engineering,
Central Terrace Salon (3rd Floor)
Abstract:
Photoemission spectra of correlated materials are usually studied using the Hubbard
model. Within the Hubbard model the spectral function of a typical correlated metal is
often characterised by a three-peak structure: a quasiparticle peak around the Fermi
level sandwiched by two satellite features, which are the signature of correlations.
These satellite features are commonly interpreted as Hubbard bands, understood
within an atomic picture as arising from a strong onsite Coulomb interaction. We
have studied the spectral functions of SrVO3 , a prototype of correlated metals, as
well as SrMoO3 using a newly developed first-principles GW+DMFT theory, a hybrid
of the GW method and the dynamical mean-field theory (DMFT). Analysis of the
results reveals that the satellite features are better understood as collective charge
excitations (plasmons) rather than Hubbard bands. We have also studied a model
sodium in which the lattice constant is artificially increased to mimic correlation
strength. Indeed, the collective plasmon picture also applies until the lattice constant
reaches 1.5 the equilibrium value, at which stage the system turns into a Mott-
Hubbard insulator. The present study suggests that the simple Hubbard band
interpretation may need to be revised by incorporating low-energy plasmons into the
picture. While the Hubbard picture is valid for systems with very localised states, the
plasmon picture may be more appropriate for systems that exhibit an itinerant
character as reflected in the quasiparticle dispersion observed in photoemission
experiments.
References
[1] F. Nilsson, L. Boehnke, Ph. Werner, and F. Aryasetiawan, Phys. Rev.
Materials 1, 043803 (2017).
[2] Ph. Werner, R. Sakuma, F. Nilsson, and F. Aryasetiawan, Phys. Rev. B 91,
125142 (2015).
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Yoshitada Morikawa,
Professor,
Department of Precision Science and Technology,
Graduate School of Engineering,
Osaka University,
2-1, Yamada-oka, Suita, Osaka 565-0871, Japan.
TEL: 06-6879-7288
FAX: 06-6879-7290
E-mail: morikawa@prec.eng.osaka-u.ac.jp
www-cp.prec.eng.osaka-u.ac.jp/
森川 良忠
大阪大学大学院工学研究科精密科学・応用物理学専攻
〒565-0871 大阪府吹田市山田丘2−1
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Abstract_Aryasetiawan_Osaka20180725.pdf