2024/04/05 by Wu, Xiao-Chuan · 2 citations
#FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Statistical Mechanics (cond-mat.stat-mech) #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2404.04331
Fluctuations of conserved quantities within a subsystem are non-local observables that provide unique insights into quantum many-body systems. In this paper, we study bipartite charge (and spin) fluctuations across interaction-driven ``metal-insulator transitions'' out of Landau Fermi liquids. The ``charge insulators'' include a class of non-Fermi-liquid states of fractionalized degrees of freedom, such as compressible composite Fermi liquids (for spinless electrons) and incompressible spin-liquid Mott insulators (for spin-1/2 electrons). We find that charge fluctuations F exhibit distinct leading-order scalings across the transition: F ∼ Llog(L) in Landau Fermi liquids and F ∼ L in charge insulators, where L is the linear size of the subsystem. In composite Fermi liquids, under certain conditions, we also identify a universal constant term -f(θ)|σxy|/(2π) when the subsystem geometry contains a sharp corner, where f(θ) denotes a function of the corner angle, and σxy is the Hall conductivity. At the critical point, provided the transition is continuous, the leading scaling F∼ L is accompanied by a subleading universal corner contribution -log(L)f(θ)Cρ/2 with the same angle dependence f(θ), and the universal coefficient Cρ is directly related to the predicted universal jumps in longitudinal and Hall resistivities. These results establish fluctuation-transport relations, paving the way for numerical and experimental studies of unconventional quantum criticalities in metals.