Nikola Machacova | Searcharxiv

arXiv2026

First principles characterization of spinterfaces between magnetic Cobaltocene molecule and 2D magnets (CrI$_3$, Fe$_3$GeTe$_2$)

In this paper, we examine the properties of spin-polarized interfaces consisting of single-molecule magnet bis(cyclopentadienyl)cobalt(II) (cobaltocene) and two-dimensional magnetic materials, semiconducting CrI$_3$ and metallic Fe$_3$GeTe$_2$, using first-principles density functional theory based calculations. Our calculated adsorption energies indicate the stability of these hetero-interfaces with the observation of hybridization of electronic states across the interface. Magnetic exchange interaction parameters have been obtained from both total energy differences and the Liechtenstein-Katsnelson-Antropov-Gubanov (LKAG) formalism in the basis of maximally localized Wannier functions (MLWFs). Analysis of these parameters shows a strong directional anisotropy in the magnetic substrate-molecule interaction in agreement with the nature of orbital hybridization. Additionally, possible exchange mechanisms are proposed based on orbital-resolved exchange and hopping parameters. We also show that the molecular adsorption may enhance the intralayer exchange interactions, with some exchange parameters reaching up to a 3-fold increase in magnitude compared to the freestanding case. Finally, we observe a 100 % spin polarization at the Fermi level in the cobaltocene/CrI$_3$ interface, which makes it particularly promising for spin-transport applications.

cond-mat.mtrl-sci↗

arXiv2025

Complex magnetic exchange, anisotropy and skyrmionic textures in two-dimensional FeXZ$_{2}$ (\textit{X} = Nb, Ta and \textit{Z} = S, Se, Te) ferromagnets

FeNbTe$_{2}$, long known as a van der Waals metallic system, has recently been resynthesized and shown to exhibit ferromagnetic order. In this study, using first-principles density functional theory (DFT), we aim to provide a deeper insight into the magnetic properties of FeNbTe$_{2}$ and its related compounds (FeXZ$_{2}$, \textit{X} = Nb, Ta; \textit{Z} = S, Se, Te), in their two-dimensional form, including their non-centrosymmetric Janus counterparts. Our results indicate that these materials are energetically, dynamically, thermally, and mechanically stable, supporting the possibility of FeNbTe$_{2}$ exfoliation and potential for experimental realization of new compounds. An evolutionary structure search suggests that FeNbTe$_{2}$ retains its monoclinic symmetry in the monolayer form. Our analysis of hopping parameters obtained from Wannierization of DFT bands shows that the nearest-neighbor magnetic interactions are primarily direct, while second-nearest and more distant interactions are mediated by the chalcogen atoms. Interestingly, although the second-nearest-neighbor interactions are smaller in magnitude, they appear to play a key role in determining the magnetic ordering in these systems. We also find evidence of canted magnetic anisotropy in FeXZ$_{2}$ compounds, with relatively strong magnetocrystalline anisotropy energy and easy-axis deviations of up to 41$^\circ$ from the out-of-plane direction-an uncommon and potentially useful feature for spintronic applications. Curie temperatures estimated from Monte Carlo simulations are below room temperature but above cryogenic levels for most compounds. Micromagnetic simulations revealed that Janus-structured FeNbSeTe can host N\'eel-type skyrmions even in the absence of an external magnetic field, making this compound a suitable candidate for further experimental studies.

cond-mat.mtrl-sci↗