Speaker
Description
2D magnetic materials have sourced great attention in the last few years [1]. Intrinsic theoretical interest arises from the very existence of magnetism below the 3D limit, proven only recently after decades of debate, as well as from the observed richness in magnetic phases, encompassing conventional ferromagnetic and antiferromagnetic as well as more exotic textures. Besides, these materials are known to offer practical applications in fields such as spintronics.
The popularity gained by such research field has driven the adaptation of first-principles approaches, combined with model Hamiltonians, to calculate exchange parameters, crucial for the prediction of magnetic textures [2]. However, the methodology is not uniquely established as of today, which results in a lack of systematicity in the data produced; as a consequence, inhomogeneous and/or incomplete predictions may arise, preventing a full comprehension of the nature of exchange interaction in some cases [3].
To address such issue, we present AMaRaNTA (Automating MAgnetic paRAmeters iN a Tensorial Approach), a computational package that systematically automates Density Functional Theory (DFT) simulations of exchange parameters for 2D magnets. Within AMaRaNTA, these are characterized by means of a nearest-neighbour exchange tensor, along with scalar parameters for the second- and third-neighbour exchange and the single-ion anisotropy. Both aspects allow us to push the research beyond the state of the art, since previous efforts in this respect were limited to nearest neighbours and partially-tensorial approaches only [4]. As of today, we have already employed AMaRaNTA to prepare a compact database of exchange parameters for around 30 materials [5].
AMaRaNTA comes in the form of an AiiDA workchain [6], based on the Vienna Ab-initio Simulation Package (VASP) for DFT calculations [7]; actual evaluation of the exchange parameters is done by post-processing DFT total energies via the so-called four-states method [2]. Ease of use is guaranteed in that the user is only required to provide a structure file; AMaRaNTA takes care of building the necessary simulation cells and, through AiiDA, to set up all calculations, retrieve the results and extract the exchange parameters.
References
[1] M. Gibertini et al., Nat. Nanotechnol. 14, 408 (2019).
[2] X. Li et al., Molecules 26, 803 (2021).
[3] J.Y. Ni et al., Phys. Rev. Lett. 127, 247204 (2021).
[4] D. Torelli et al., npj Comput. Mater. 6, 158 (2020).
[5] F. Orlando et al. (manuscript in preparation).
[6] G. Pizzi et al., Computational Materials Science, 111, 218 (2016).
[7] G. Kresse and J. Furthmüller, Phys. Rev. B 54, 11169 (1996)
