Importance of electronic correlations for the magnetic properties of the two-dimensional ferromagnet CoBr${}_2$

Abstract

We investigate the emergence of ferromagnetism in the two-dimensional metal-halide CoBr${}_2$, with a special focus on the role of electronic correlations. The calculated phonon spectrum shows that the system is thermodynamically stable unlike other Co halides. We apply two well-known methods for the estimation of the Curie temperature. First, we do DFT+U calculations to calculate exchange couplings, which are subsequently used in a classical Monte Carlo simulation of the resulting Ising spin model. The transition temperature calculated in this way is in the order of 100 K, but shows a strong dependence on the choice of interaction parameters. Second, we apply dynamical mean-field theory to calculate the correlated electronic structure and estimate the transition temperature.This results in a similar estimate for a noticeable transition temperature of approximately 100 K,however, without the strong dependence on the interaction parameters. The effect of electron-electron interactions are strongly orbital selective, with only moderate correlations in the three low-lying orbitals (one doublet plus one singlet), and strong correlations in the doublet at higher energy. This can be traced back to the electronic occupation in DMFT, with five electrons in the three low-lying orbitals and two electrons in the high-energy doublet, making the latter one half-filled. Nevertheless, the overall spectral gap is governed by the small gap originating from the low-lying doublet+singlet orbitals, which changes very weakly with interaction U. In that sense,the system is close to a Mott metal-to-insulator transition, which has been shown previously to be a hot-spot for strong magnetism.

References in corpus (27)

• Layer-dependent Ferromagnetism in a van der Waals Crystal down to the Monolayer Limit
• Discovery of intrinsic ferromagnetism in 2D van der Waals crystals
• Two-dimensional materials from high-throughput computational exfoliation of experimentally known compounds
• Probing magnetism in 2D van der Waals crystalline insulators via electron tunneling
• Strong electronic correlations from Hund's coupling
• TRIQS: A Toolbox for Research on Interacting Quantum Systems
• Hybridization expansion impurity solver: General formulation and application to Kondo lattice and two-orbital models
• Dynamical Mean-Field Theory within an Augmented Plane-Wave Framework: Assessing Electronic Correlations in the Iron Pnictide LaFeAsO
• Interplay between Kitaev interaction and single ion anisotropy in ferromagnetic CrI${}_3$ and CrGeTe${}_3$ monolayers
• TRIQS/CTHYB: A Continuous-Time Quantum Monte Carlo Hybridization Expansion Solver for Quantum Impurity Problems
• Electronic structure and magnetism of transition metal dihalides: bulk to monolayer
• TRIQS/DFTTools: A TRIQS application for ab initio calculations of correlated materials
• Spin direction controlled electronic band structure in two dimensional ferromagnetic CrI3
• Importance of electronic correlations for structural and magnetic properties of the iron pnictide superconductor LaFeAsO
• A family of high-temperature ferromagnetic monolayers with locked spin-dichroism-mobility anisotropy: MnNX and CrCX (X=Cl, Br, I; C=S, Se, Te)
• Calculating critical temperatures for ferromagnetic order in two-dimensional materials
• Maximum entropy formalism for the analytic continuation of matrix-valued Green's functions
• Screening magnetic two-dimensional atomic crystals with nontrivial electronic topology
• Origin of the high Neel temperature in SrTcO3
• Curie Temperature of Emerging Two-Dimensional Magnetic Structures
• Intrinsic ferromagnetism and quantum anomalous Hall effect in CoBr2 monolayer
• Spin-density functional theories and their $+U$ and $+J$ extensions: a comparative study of transition metals and transition metal oxides
• Enhancement of the Na${}_x$CoO${}_2$ thermopower due to electronic correlations
• The low-energy ARPES and heat capacity of Na${}_{0.3}$CoO${}_2$: A DMFT study
• Rotationally-Invariant Exchange Interaction: The Case of Paramagnetic Iron
• Theoretical prediction of antiferromagnetism in layered perovskite Sr${}_2$TcO${}_4$
• Theoretical investigation on the ferromagnetic two-dimensional scandium monochloride sheet that has a high Curie temperature and could be exfoliated from a known material

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