Negative electron compressibility in the Hubbard model

• Published in: Physica scripta Vol. 95; no. 1; pp. 15806 - 15811
• Main Author: Sherman, A
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.01.2020
• Subjects: negative electron compressibility; one-band repulsive Hubbard model; strong coupling diagram technique
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/ab401a

Using the strong coupling diagram technique, we study the one-band repulsive Hubbard model on a two-dimensional square lattice in a wide range of chemical potentials . Infinite sequences of diagrams describing interactions of electrons with spin and charge fluctuations are taken into account. At low temperatures, regions of the negative electron compressibility are found for 0 and U, where U is the Hubbard repulsion. They are manifestations of non-rigid electron bands, which change drastically in the mentioned regions of chemical potentials due to the level crossing in the Hubbard atom.