Magnetic state of the bulk, surface and nanoclusters of CaMnO3: A DFT study |
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Authors: | Thuy Trang NguyenThanh Cong Bach Huong Thao PhamThe Tan Pham Duc Tho NguyenNam Nhat Hoang |
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Institution: | a Faculty of Physics, Hanoi University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Ha Noi, Viet Nam b Faculty of Basic Science, Hung Yen University of Technology and Education, Hung Yen, Viet Nam c Faculty of Technical Physics and Nanotechnology, University of Engineering and Technology, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, Ha Noi, Viet Nam |
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Abstract: | The electronic structures of bulk, 2D slabs and clusters of CaMnO3 in various magnetic configurations are presented. The obtained results including optimized cell constant, band-gap, Mn magnetic moment, on-site Coulomb repulsion potential and p-d charge separation potential are in good agreement with experiment data. The energetically most preferable configuration was an insulating charge-transfer ground state with G-type antiferromagnetic (AF) configuration (classified according to Wollan and Koehler, Phys. Rev. 100 (1955) 545). For the finite 2D layers the C-type AF ground state was found to be most stable. The surface effect on magnetism of finite quasi 2D systems appeared to originate in the pyramidal field splitting of Mn 3d levels, which induced the formation of ferromagnetic (FM) regions within the AF matrix and the extension of FM correlation deep through 7 subsurface layers (2.7 nm from the surface). All finite systems (clusters and slabs) were found non-conducting due to the localization of electrons and the cancellation of surface excess carriers (holes) after surface relaxation, although the band-gaps of 2D systems were sufficiently reduced in comparison with that of the bulk. |
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Keywords: | DFT Magnetic properties Electronic structure Cluster Surfaces |
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