Charge compressibility and quantum magnetic phase transition in MoS$_2$

TL;DR

This paper studies the ground-state properties of monolayer MoS₂, revealing non-monotonic charge compressibility behavior and a quantum phase transition from paramagnetic to ferromagnetic states influenced by Coulomb and short-range interactions.

Contribution

It introduces a detailed mean-field analysis of MoS₂ considering Coulomb and intervalley interactions, highlighting novel compressibility behavior and magnetic phase transitions.

Findings

Non-monotonic charge compressibility as a function of carrier density.

Identification of a paramagnetic-to-ferromagnetic quantum phase transition.

Dependence of properties on dielectric constant, charge density, and Hubbard repulsion.

Abstract

We investigate the ground-state properties of monolayer MoS$_2$ incorporating the Coulomb interaction together with a short-range intervalley interaction between charged particles between two valleys within the Hartree-Fock approximation. We consider four variables as independent parameters, namely homogeneous charge (electron or hole) density, averaged dielectric constant, spin degree of freedom and finally the Hubbard repulsion coefficient which originates mostly from $4d$ orbits of Mo atoms. We find the electronic charge compressibility within the mean-field approximation and show that non-monotonic behavior of the compressibility as a function of carrier density which is rather different from those of the two-dimensional electron gas. We also explore a paramagnetic-to-ferromagnetic quantum phase transition for the wide range of the electron density in the parameter space.