| 1. |
- Cossu, Fabrizio, et al.
(författare)
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Strain-induced stripe phase in charge-ordered single layer NbSe2
- 2020
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Ingår i: NPG ASIA MATERIALS. - : NATURE PUBLISHING GROUP. - 1884-4049 .- 1884-4057. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Charge density waves are ubiquitous phenomena in metallic transition metal dichalcogenides. In NbSe2, a triangular 3x3 structural modulation is coupled to a charge modulation. Recent experiments reported evidence for a triangular-stripe transition at the surface, due to strain or accidental doping and associated to a 4x4 modulation. We employ ab initio calculations to investigate the strain-induced structural instabilities in a pristine single layer and analyse the energy hierarchy of the structural and charge modulations. Our results support the observation of phase separation between triangular and stripe phases in 1H-NbSe2, relating the stripe phase to compressive isotropic strain, favouring the 4x4 modulation. The observed wavelength of the charge modulation is also reproduced with a good accuracy.
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| 2. |
- Hofer, Werner A, et al.
(författare)
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Detection of spin-states in Mn-oped gallium arsenide films
- 2007
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Ingår i: Nanotechnology. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- We show that isolated magnetic dipoles centred at the position of manganese impurities in a gallium arsenide lattice lead to spin polarized states in the bandgap of the III-V semiconductor. Spectroscopy simulations with a tungsten tip agree well with experimental data; in this case, no difference can be observed for the two magnetic groundstates. But if the signal is read with a magnetic iron tip, it changes by a factor of up to 20, depending on the magnetic orientation of the Mn atom.
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| 3. |
- Niu, Kaifeng, et al.
(författare)
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On-surface synthesis of 2D COFs via molecular assembly directed photocycloadditions: a first-principles investigation
- 2021
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Ingår i: Journal of Physics. - : IOP PUBLISHING LTD. - 0953-8984 .- 1361-648X. ; 33:47
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Tidskriftsartikel (refereegranskat)abstract
- Over the past decades, the rational synthesis of two-dimensional covalent organic framework (2D COFs) monolayer via on-surface chemistry has been widely explored. Herein, we propose the [2 + 2] photocycloaddition as a novel strategy for large-scale fabrication of COFs from theoretical perspective. Thanks to the symmetry forbidden of thermal [2 + 2] cycloaddition, the molecular precursors carrying vinyl groups will not chemically interact with each other during thermal annealing, which is essential to achieve molecular assembly. The subsequent photocycloaddition of these precursors may produce large-scale 2D COFs at low temperatures, in which the symmetry of molecular assembly remains unchanged. Our results show that 2D COFs can be produced via [2 + 2] photocycloadditions directed from self-assembled precursors, in which alkylbenzene molecules with vinyl groups on side chains exhibit appropriate intermolecular distances. By performing high-throughput calculations, several promising molecular precursors are proposed to achieve large-scale 2D COFs. This work provides an applicable strategy for the large-scale synthesis of 2D carbon materials.
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