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Title: 2D rare-earth metal carbides (MXenes) Mo 2 NdC 2 T 2 electronic structure and magnetic properties: A DFT + U study
2D rare-earth metal carbides (MXenes) are attractive due to their novel electronic and magnetic properties and their potential as scalable 2D magnets. In this study, we used density functional theory with the Hubbard U correction to characterize the structure, termination, and magnetism in an out-of-plane ordered rare-earth containing M 3 C 2 T x MXene, Mo 2 NdC 2 T 2 (T = O or OH). We investigated the effect of the U parameter on the stability and magnetism of two possible termination sites: the hollow sites aligned with the inner Nd atoms (Nd-hollow sites) and those aligned with the closest C atoms (C-hollow sites). We found that increasing U Mo stabilized the Nd hollow sites, which minimized electrostatic repulsion between C and O atoms. Using U Mo  = 3.0 eV and U Nd  = 5.6 eV, obtained via the linear response method, we found that the energetically preferred termination site was C-hollow in Mo 2 NdC 2 O 2 and Nd-hollow in Mo 2 NdC 2 (OH) 2 . Regardless of termination and the Hubbard U value, we found Mo 2 NdC 2 O 2 and Mo 2 NdC 2 (OH) 2 to be magnetic. The C-hollow termination resulted in ferromagnetic states for all Hubbard U tested with no magnetic moment in Mo. In the case of Nd-hollow, Mo became magnetic for U Mo  ≥ 4 eV. The difference of Mo magnetism in Nd-hollow and C-hollow was explained by crystal field splitting of the Mo d orbital caused by a distorted ligand.  more » « less
Award ID(s):
2124478 2124241
PAR ID:
10436777
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Journal of Applied Physics
Volume:
132
Issue:
20
ISSN:
0021-8979
Page Range / eLocation ID:
204301
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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