Fatemeh Haddadi^1,2*, Edward Linscott^1*, Iurii Timrov^1,2*, Nicola Marzari^1,2*, Marco Gibertini^3,4*

1 Theory and Simulation of Materials (THEOS), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

2 National Centre for Computational Design and Discovery of Novel Materials (MARVEL)

3 Dipartimento di Scienze Fisiche, Informatiche e Matematiche, University of Modena and Reggio Emilia, I-41125 Modena, Italy

4 Centro S3, CNR-Istituto Nanoscienze, I-41125 Modena, Italy

* Corresponding authors emails: fatemeh.haddadi@epfl.ch, edward.linscott@epfl.ch, iurii.timrov@epfl.ch, nicola.marzari@epfl.ch, marco.gibertini@unimore.it

DOI10.24435/materialscloud:ez-6k [version v1]

Publication date: Jan 30, 2024

How to cite this record

Fatemeh Haddadi, Edward Linscott, Iurii Timrov, Nicola Marzari, Marco Gibertini, On-site and inter-site Hubbard corrections in magnetic monolayers: The case of FePS₃ and CrI₃, Materials Cloud Archive 2024.18 (2024), https://doi.org/10.24435/materialscloud:ez-6k

Description

Hubbard-corrected density-functional theory has proven to be successful in addressing self-interaction errors in 3D magnetic materials. However, the effectiveness of this approach for 2D magnetic materials has not been extensively explored. Here, we use PBEsol+U and its extensions PBEsol+U+V to investigate the electronic, structural, and vibrational properties of 2D antiferromagnetic FePS₃ and ferromagnetic CrI₃, and compare the monolayers with their bulk counterparts. Hubbard parameters (on-site U and inter-site V) are computed self-consistently using density-functional perturbation theory, thus avoiding any empirical assumptions. We show that for FePS₃ the Hubbard corrections are crucial in obtaining the experimentally observed insulating state with the correct crystal symmetry, providing also vibrational frequencies in good agreement with Raman experiments. While empirical U can lead to an unstable ground-state (i.e. imaginary phonons), the system remains stable through the self-consistent process of calculating Hubbard parameters. For ferromagnetic CrI₃, we discuss how a straightforward application of Hubbard corrections worsens the results and introduces a spurious separation between spin-majority and minority conduction bands. Promoting the Hubbard U to be a spin-resolved parameter — that is, applying different (first-principles) values to the spin-up and spin-down manifolds — recovers a more physical picture of the electronic bands and delivers the best comparison with experiments.

Materials Cloud sections using this data

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Keywords

DFT DFT+U DFT+U+V first principles Hubbard 2D materials 2D magnets cscs MARVEL/DD3 EPFL Quantum ESPRESSO