Organising strong correlations in electronic, spin, and local moment systems
Lundi 10/12/2018, 11:00-12:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
We present a framework for organising the correlations of interacting electrons, which provides access to a novel regime of strongly correlated behaviour. Following an introduction, we highlight two ways to characterise the electronic degree of freedom, either by the canonical fermion algebra or by the graded Lie algebra su(2|2). The first underlies Landau's Fermi liquid description of correlated matter, and we identify an alternative Fermi liquid regime governed by the latter. We exploit the su(2|2) algebra to derive a systematic expansion of the electronic correlations, and describe the resulting leading approximations to electronic spectral function. These reveal a splitting in two of the electronic band, a violation of the Luttinger sum rule, and a Mott metal-insulator transition. We conclude with a reinterpretation of the meaning of the term ``strongly correlated'', and offer a scheme which encompasses magnetic, electronic, and local moment systems.