Simultaneous switches of out-of-plane and in-plane ferroelectric polarizations by sliding, as well as the moiré effect, are observed in Janus bilayer MoSSe.

Spin caloritronic devices based on magnetic graphether nanoribbons exhibit a robust spin-dependent Seebeck effect and a remarkable spin thermoelectric performance, including a high spin Seebeck coefficient and a giant spin figure of merit.

Different from the honeycomb monolayer (like graphene), the single-layer boron chalcogenide B2X3 (X = S, Se, Te) exhibits a kagome lattice. Using the first-principles calculations, the existence of sliding ferroelectricity in van der Waals kagome-B2X3 bilayers is demonstrated. The sliding ferroelectricity results from the breaking of the inversion symmetry by interlayer sliding. In addition, there are multiple stable states in a unit cell for kagome-lattice bilayers. The bandgap is found to vary with sliding distance. By choosing specific pathways, not only the out-of-plane polarization but also the in-plane polarization can be reversed by interlayer sliding. Such a simultaneous reversal for both in-plane and out-of-plane polarizations by sliding would be useful for applications in various devices. These behaviors are found in all the three configurations (X = S, Se, Te), suggesting they are the intrinsic features of such systems and may throw light on the development of future devices.

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 CrI${}_3$ 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.

For CMOS electronics, the channel materials – which can offer symmetrical performance for n- and p-type devices, along with the ability to scale transistors down to the ultra-scale limit – are crucial in the next era beyond silicon. Monolayer KMgX (X = P, As, Sb) not only possesses an atomically thin structure, but also exhibits high mobility for both electrons and holes; being advantageous for symmetrical performance and shrinking a device’s size. Based on first-principles calculations, the device performance limit of sub-5 nm monolayer KMgX (X = P, As, Sb) metal–oxide semiconductor field-effect transistors (MOSFETs) with a double-gated setup are investigated. The results show that, for all three KMgX configurations (X = P, As, Sb), both n- and p-type MOSFETs can meet the ITRS 2013 requirements for 2028 horizon in high-performance applications, even as L_g reduces to 3 nm. The ON-state currents of those systems exceed the performance of most previously reported monolayer MOSFETs. In particular, the 5 nm-L_g n-type KMgSb and KMgAs MOSFETs exhibit ultra-high ON-state currents of 3463 and 3248 μA μm⁻¹, respectively. Furthermore, the ratios of subthreshold swing, ON-state current, fringe capacitance, delay time, and power-delay product between n- and p-type devices, demonstrate a high degree of symmetry. Our results suggest that the use of monolayer KMgX (X = P, As, Sb) MOSFETs would be highly advantageous for the development of sub-5 nm homogeneous CMOS electronics.