Fig. 6 Crystal structure and Jij interactions of bulk Fe3GeTe2
该文近期发布于npj Computational Materials 9: 85(2023)。
Fig. 7 Density of states D(?) of Fe3GeTe2 bulk.
Editorial Summary DMFT: Accurate calculation of 2D magnetic materials In recent years, two-dimensional van der Waals materials have attracted extensive attention due to their intriguing properties. FenGeTe2(FGT), a recently discovered class of two-dimensional van der Waals material, exhibits magnetic behavior at room temperature. However, subsystems belonging to FGT class display site-dependent magnetic properties, necessitating an accurate assessment of their magnetic and electronic effects. The main peculiarity related to all the FGT systems is their site-dependent magnetic and electronic properties. In other words, based on the magnetic moments associated with different Fe sublattices, electrons belonging to some Fe atoms are expected to have more itinerant character than others. Up to this date, researchers have used DFT, DFT?+?U or DMFT approaches, leaving behind the most crucial question unanswered, i.e., which method is the most reliable one to correctly treat the FGT systems.
Fig. 8 Spectral functi on S(k, ?) for bulk Fe3GeTe2.
Sukanya Ghosh et al from the Department of Physics and Astronomy, Uppsala University, performed a first-principles study on the electronic structures and magnetic properties of FenGeTe2 (n?=?3,?4,?and 5) systems by GGA, LSDA, GGA?+?U and GGA?+?DMFT methods. The results indicated that GGA + U with static electronic correlation yields substantial deviations in lattice parameters, magnetic moments, and Curie temperatures compared to experimental values, rendering it unsuitable for FGT systems. Standard GGA reproduces magnetic moments consistent with experiment, but overestimates Curie temperatures significantly. Upon the inclusion of dynamical electronic correlations within the GGA?+?DMFT approach, the magnetic moments remain almost unchanged, while the exchange interactions, especially the isotropic symmetric exchange parameters get significantly modified to decrease the Curie temperature substantially to have a nice agreement with the experimental results. This study demonstrates that the consideration of dynamical correlations is necessary to capture the correct electronic structure and magnetic behavior of FGT systems. This article was recently published in npj Computational Materials 9: 86 (2023).
Unraveling effects of electron correlation in two-dimensional FenGeTe2(n?=?3, 4, 5) by dynamical mean field theory（用动态平均场论阐明二维FenGeTe2（n=3,4,5）中的电子关联效应） Sukanya Ghosh, Soheil Ershadrad, Vladislav Borisov & Biplab Sanyal Abstract The FenGeTe2systems are recently discovered two-dimensional van-der-Waals materials, exhibiting magnetism at room temperature. The sub-systems belonging to FenGeTe2class are special because they show site-dependent magnetic behavior. We focus on the critical evaluation of magnetic properties and electron correlation effects in FenGeTe2 (n?=?3, 4, 5) (FGT) systems performing first-principles calculations. Three different ab initio approaches have been used primarily, viz., (i) standard density functional theory (GGA), (ii) incorporating static electron correlation (GGA?+?U) and (iii) inclusion of dynamic electron correlation effect (GGA?+?DMFT).
Our results show that GGA?+?DMFT is the more accurate technique to correctly reproduce the magnetic interactions, experimentally observed transition temperatures and electronic properties. The inaccurate values of magnetic moments, exchange interactions obtained from GGA?+?U make this method inapplicable for the FGT family. Correct determination of magnetic properties for this class of materials is important since they are promising candidates for spin transport and spintronic applications at room temperature.