Nanoribbons (NRs) of two-dimensional (2D) materials have attracted intensive research interests because of exotic physical properties at edges as well as tunable properties via width control. In this paper, using density functional theory (DFT) calculations, we discover sensitive dependence of magnetic properties of 1T′-MoS2 NRs, that is, periodic variation of magnetic moments between 0.1 and 1.2 μ B , on NR width (even or odd number of MoS2 units). Our results reveal that a special edge reconstruction, which is not recognized before, stabilizes the ferromagnetic (FM) ground state. Our results also suggest that the FM state could be stable under ambient condition. This study indicates a promising means to integrate multiple magnetic units for small-scale functional devices, such as information storage and spintronics, on a single piece of MoS2 NR by designing segments with different width.

Lateral heterostructures of two-dimensional (2D) materials, integrating different phases or materials into a single piece of nanosheet, have attracted intensive research interests for electronic devices. Extending the 2D lateral heterostructures to spintronics demands more diverse electromagnetic properties of 2D materials. In this paper, using density functional theory calculations, we survey all IV, V, and VI group transition metal dichalcogenides (TMDs) and discover that CrS2 has the most diverse electronic and magnetic properties: antiferromagnetic (AFM) metallic 1T phase, non-magnetic (NM) semiconductor 2H phase, and ferromagnetic (FM) semiconductor 1T′ phase with a Curie temperature of ~1000 K. Interestingly, we find that a tensile or compressive strain can turn the 1T′ phase into a spin-up or spin-down half-metal. Such strain tunability can be attributed to the lattice deformation under tensile/compressive strain that selectively promotes the spin-up/spin-down VBM (valence band bottom) orbital interactions. The diverse electromagnetic properties and the strain tunability enable strain-controlled spintronic devices using a single piece of CrS2 nanosheet with improved energy efficiency. As a demo, a prototypical design of the spin-valve logic device is presented. It offers a promising solution to address the challenge of high energy consumption in miniaturized spintronic devices.

Charge doping could effectively modulate the charge density wave state of monolayer MoS2 with large strain output and superelasticity.

Doping of nanomaterials has become a versatile approach to tailoring their physical and chemical properties, leading to the emerging fields of solotronics and quantumcontrolled catalysis. These extraordinary functionalities critically depend on the atomic arrangements and dynamic behaviors of dopants, which are however challenging to probe due to the ultrasmall volume of hosting nanomaterials and the even smaller scale of doping-induced structure variations. Here, we reveal the characteristic configurations of Ce dopants and their correlation with the remarkably enhanced oxygen-exchange capacity in <10 nm Mn 3 O 4 nanoparticles. The element and oxidation-state sensitivity and quantification capability of atomic-resolution electron energy-loss spectroscopic mapping allow an unambiguous determination of substitutional solitary Ce dopants and CeO 2 nanoclusters inside the charge-ordered Mn 3 O 4 matrix, as well as single-atomic-layer CeO x on the surface. The observed high mobility of Ce dopants further illustrates an effective pathway for the conversion among various dopant nanophases. Our observation provides atomic-scale evidence of the oxygenexchange mechanism through dopant migration in Ce-doped Mn 3 O 4 nanoparticles, which rationalizes their superior redox efficiency and oxygen-exchange capacity for thermochemical synthesis of solar fuels. The demonstrated characterization strategy capable of directly probing local atomic and electronic structures of dopants can be widely applied to the investigation of structure−property interplay in other doping-engineered nanomaterials.

No abstract