Breakdown of charge homogeneity in the two-dimensional Hubbard model: Slave-boson study of magnetic order

Seufert, Jannis; Riegler, David; Klett, Michael; Thomale, Ronny; Wölfle, P.

doi:10.1103/physrevb.103.165117

Cited by 7 publications

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“…In the course of considering incommensurate spiral phases-which allow to lower the energy of the lightly doped one-band Hubbard model with respect to the commensurate antiferromagnetic phase-negative compressibility in a small density range close to half band filling was discovered [39]. Motivated by the quest of thermodynamically stable phases a Maxwell construction was suggested, which has been recently revisited [40].…”

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Bad metal and negative compressibility transitions in a two-band Hubbard model

Fresard,

Steffen,

Kopp

2022

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We analyze the paramagnetic state of a two-band Hubbard model with finite Hund's coupling close to integer filling at n = 2 in two spacial dimensions. Previously, a Mott metal-insulator transition was established at n = 2 with a coexistence region of a metallic and a bad metal state in the vicinity of that integer filling. The coexistence region ends at a critical point beyond which a charge instability persists. Here we investigate the transition into negative electronic compressibility states for an extended filling range close to n = 2 within a slave boson setup. We analyze the separate contributions from the (fermionic) quasiparticles and the (bosonic) multiparticle incoherent background and find that the total compressibility depends on a subtle interplay between the quasiparticle excitations and collective fields. Implementing a Blume-Emery-Griffiths model approach for the slave bosons, which mimics the bosonic fields by Ising-like pseudospins, we suggest a feedback mechanism between these fields and the fermionic degrees of freedom. We argue that the negative compressibility can be sustained for heterostructures of such strongly correlated planes and results in a large capacitance of these structures. The strong density dependence of these capacitances allows to tune them through small electronic density variations. Moreover, by resistive switching from a Mott insulating state to a metallic state through short electric pulses, transitions between fairly different capacitances are within reach. I. INTRODUCTION.

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