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Dynamical behavior across the Mott transition of two bands with different bandwidths (Articolo in rivista)

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Dynamical behavior across the Mott transition of two bands with different bandwidths (Articolo in rivista) (literal)

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Ferrero, M; Becca, F; Fabrizio, M; Capone, M (2005)
Dynamical behavior across the Mott transition of two bands with different bandwidths
in Physical review. B, Condensed matter and materials physics; APS, American physical society, College Park, MD (Stati Uniti d'America)
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[ 1 ] INFM Democritos, Natl Simulat Ctr, I-34014 Trieste, Italy [ 2 ] SISSA, Int Sch Adv Studies, I-34014 Trieste, Italy [ 3 ] ICTP, I-34014 Trieste, Italy [ 4 ] Univ Roma La Sapienza, INFM, SMC, I-00185 Rome, Italy [ 5 ] Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy [ 6 ] CNR, Ist Sistemi Complessi, I-00185 Rome, Italy (literal)

Titolo

Dynamical behavior across the Mott transition of two bands with different bandwidths (literal)

Abstract

We investigate the role of the bandwidth difference in the Mott metal-insulator transition of a two-band Hubbard model in the limit of infinite dimensions by means of a Gutzwiller variational wave function as well as by dynamical mean-field theory. The variational calculation predicts a two-stage quenching of the charge degrees of freedom, in which the narrower band undergoes a Mott transition before the wider one, both in the presence and in the absence of a Hund's exchange coupling. However, this scenario is not fully confirmed by the dynamical mean-field theory calculation, which shows that, although the quasiparticle residue of the narrower band is zero within our numerical accuracy, low-energy spectral weight still exists inside the Mott-Hubbard gap, concentrated into two peaks symmetric around the chemical potential. This spectral weight vanishes only when the wider band ceases to conduct too. Although our results are compatible with several scenarios-e.g., a narrow-gap semiconductor or a semimetal-we argue that the most plausible one is that the two peaks coexist with a narrow resonance tied at the chemical potential, with a spectral weight below our numerical accuracy. This quasiparticle resonance is expected to vanish when the wider band undergoes the Mott transition. (literal)

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