Anomalous Hall conductivity control in Mn$_3$NiN antiperovskite by epitaxial strain along the kagome plane

Abstract

Antiferromagnetic manganese-based nitride antiperovskites, such as Mn3NiN, hold a triangular frustrated magnetic ordering over their kagome lattice formed by the Mn atoms along the (111)plane. As such, frustration imposes a non-trivial interplay between the symmetric and asymmetric magnetic interactions, which can only reach equilibrium in a noncollinear magnetic configuration. Consequently, the associated electronic interactions and their possible tuning by external constraints, such as applied epitaxial strain, play a crucial role in defining the microscopic and macroscopic properties of such topological condensed matter systems. Thus, in the present work, we explored and explained the effect of the epitaxial strain imposed within the (111)-plane, in which the magnetic and crystallographic symmetry operations are kept fixed, and only the magnitude of the ionic and electronic interactions are tuned. We found a linear shifting in the energy of the band structure and a linear increase/decrease of the available states near the Fermi level with the applied strain. Concretely, the compression strain reduces the Mn-Mn distances in the (111) kagome plane but linearly increases the separation between the stacked kagome lattices and the available states near the Fermi level. Despite the linear controlling of the available states across the Fermi energy, the anomalous Hall conductivity shows a non-linear behavior where the σ111 conductivity nearly vanishes for tensile strain. On the other hand, σ111 fetches a maximum increase of 26% about the unstrained structure for a compression value close to −1.5%. This behavior found an explanation in the non-divergent Berry curvature within the kagome plane, which is increased for constraining but significantly reduced for expansion strain values. Our results indicate a distinct correlation between the anomalous Hall conductivity and the Berry curvature along the (111)-plane as a function of the strain. The Berry curvature acts as the source and the strain as the control mechanism of this anomalous transport phenomenon.

Chiral magnetism, lattice dynamics, and anomalous Hall conductivity in V3AuN antiferromagnetic antiperovskite

“…Evidently, this value is considerably smaller than the reported one. For example, in the Mn 3 NiN case, D. Torres-Amaris et al [51] showed that under the PBEsol+U scheme, as shown here, the AHC is σ xy = 68 S•cm −1 , in better agreement with the experimentally reported value of σ xy = 22 S•cm −1 in thin-films [67], and considerably smaller than the calculated value of σ xy = 130-170 S•cm −1 in Refs. [67,68] where no correction was considered.…”

“…Thus, as indicated by our results and by W. Rieger et al [44], such an Au-centered structure is considerably higher in energy, and the N-centered structure is potentially the crystallographic ground state. As observed in the Mn 3 NiN antiperovskite, it is recommended to correct the electronic exchange-correlation by including the Coulomb U repulsion parameter in the magnetically active cation to adequately reproduce the vibrational, structural, and electronic degrees of freedom in the V 3 AuN [6,51]. Along these lines, we have fully relaxed the electronic and atomic structure of the V 3 AuN compound within the metaGGA SCAN-based exchangecorrelation [33] and we obtained a relaxed lattice parameter of 3.961 Å in good agreement with the experimentally reported value of a = 3.962 Å [44].…”

“…Furthermore, at this point, it is worth commenting that in most of the reported literature, the calculations have been performed within the PBE approach, and no Hubbard term has been considered; and therefore, a no electronic correction has been explored, aiming to remove the computational chemical pressure and to obtain fully relaxed lattice parameters [49,50,67,68]. Thus, the exchange-correlation energy, which strongly influences the magnetic and electronic structure, has not been included considering the Coulomb repulsion value U , which, based on our analysis, tends to considerably reduce the bands spreading and, therefore, affects the electronic structure close to the Fermi level and reduces the computed AHC values [6,51]. Moreover, this exchange-correlation correction affects the structural parameters where the experimentally observed lattice parameter can be obtained after carefully introducing the PBEsol+U methodology, as discussed above.…”