Mott physics and spin fluctuations: a unified framework

Abstract : We present a formalism for strongly correlated electrons systems which consists in a local approximation of the dynamical three-leg interaction vertex. This vertex is self-consistently computed with a quantum impurity model with dynamical interactions in the charge and spin channels, similar to dynamical mean field theory (DMFT) approaches. The electronic self-energy and the polarization are both frequency and momentum dependent. The method interpolates between the spin-fluctuation or GW approximations at weak coupling and the atomic limit at strong coupling. We apply the formalism to the Hubbard model on a two-dimensional square lattice and show that as interactions are increased towards the Mott insulating state, the local vertex acquires a strong frequency dependence, driving the system to a Mott transition, while at low enough temperatures the momentum-dependence of the self-energy is enhanced due to large spin fluctuations. Upon doping, we find a Fermi arc in the one-particle spectral function, which is one signature of the pseudo-gap state.
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Submitted on : Monday, November 23, 2015 - 3:04:50 PM
Last modification on : Thursday, February 7, 2019 - 2:55:53 PM

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Thomas Ayral, Olivier Parcollet. Mott physics and spin fluctuations: a unified framework. Physical Review B : Condensed matter and materials physics, American Physical Society, 2015, 92, pp.115109. ⟨10.1103/PhysRevB.92.115109 ⟩. ⟨cea-01232442⟩

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