Due to the weak van der Waals (vdW) interlayer interaction, interfacial geometry of two-dimensional (2D) magnetic vdW materials can be freely assembled, and the stacking order between layers can be readily controlled, such as laterally shifting or rotating, which may trigger the variation of magnetic order. We investigate the H-type bilayer CrI3 where the two layers are aligned in anti-parallel directions. Based on first-principles calculations, we propose two states with different interlayer magnetic couplings, i.e., ferromagnetic and antiferromagnetic, and analyze the superexchange mechanism inside. It is found that the two magnetic coupling states are stacking-dependent, and could be switched by applying out-of-plane axial strain and electron doping. Our findings show great application potential in the design of heterostructural and spintronic devices based on 2D magnetic vdW materials.

Graphether, a two-dimensional oxocarbon monolayer, has attracted wide attention due to its excellent mechanical, thermal, and electrical performance. Armchair-edged graphether nanoribbons (AGENRs) are investigated through first-principles calculations. It is found that symmetry plays a key role in band structures, which could trigger an indirect–direct transition of the bandgap, following the odd–even parity of the nanoribbon. Furthermore, the asymmetrical electronic structure caused by edge hydrogen passivation would induce semiconducting–metallic transition. Our findings imply that the electronic structure properties of AGENRs could be modulated by symmetry, which may throw light on the band engineering of related devices and the design of heterostructures.

The generation of spin currents is a significant issue in spintronics. A spin current can be induced by a temperature gradient in the spin-dependent Seebeck effect, which has attracted growing...

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Controlling the spin transport at the single-molecule level, especially without the use of ferromagnetic contacts, becomes a focus of research in spintronics. Inspired by the progress on atomic-level molecular synthesis, through first-principles calculations, we investigate the spin-dependent electronic transport of graphene nanoflakes with side-bonded functional groups, contacted by atomic carbon chain electrodes. It is found that, by rotating the functional group, the spin polarization of the transmission at the Fermi level could be switched between completely polarized and unpolarized states. Moreover, the transition between spin-up and spin-down polarized states can also be achieved, operating as a dual-spin filter. Further analysis shows that, it is the spin-dependent shift of density of states, caused by the rotation, that triggers the shift of transmission peaks, and then results in the variation of spin polarization. Such a feature is found to be robust to the length of the nanoflake and the electrode material, showing great application potential. Those findings may throw light on the development of spintronic devices.