The thickness dependence of the chemical and physical properties is one fundamental characteristic shared by many twodimensional layered transition-metal dichalcogenides, including molybdenum disulfide (MoS 2 ). Recently, in order to expand the scope of applications of MoS 2 , surface functionalization has been employed to engineer its chemical and electrical properties for the purposes of drug delivery, photothermal therapy, gas sensing, and biosensing. Here, we report a facile method for controlled functionalization of MoS 2 fieldeffect transistors of a wide range of thicknesses with α-lipoic acid (LA). Atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) show evidence of chemical bonding. After functionalization, a significant increase of on current is observed in the MoS 2 transistors, caused by the enhancement of electronic mobility. The maximum increase of mobility can reach ∼100% for monolayer devices. The thickness dependence of the mobility enhancement is analyzed, and a theoretical model based on vacancy filling and charge impurity scattering is proposed to reveal the microscopic origin. These results provide new opportunities of controlling the electronic properties of MoS 2 by surface functionalization.

Bilayer graphene (BLG) shows great application prospect and potential in next-generation electronics because of its unique electrical and mechanical properties. However, the scalable synthesis of large-area high-quality BLG films is still a great challenge, despite the maturity of chemical vapor deposition (CVD) technique. In this study, we report a robust method to grow BLGs on flat, softened Cu foils by atmospheric pressure CVD. A moderate amount of residual oxygen accelerates the growth of BLG domains while suppressing the formation of multilayers. Raising the nucleation density at low hydrogen pressure efficiently increases the film continuity. Based on the optimized CVD process, the growth of graphene films on 4×4 cm 2 Cu foils with an average BLG coverage of 76% is achieved. The morphology and structure characterizations demonstrate a high quality of the BLG. Dual gate field-effect transistors are investigated based on AB-stacked BLG, with a tunable bandgap and high carrier mobility of up to 6790 cm 2 V −1 s −1 at room temperature.

1 Novel materials incorporating electronic degrees of freedom other than charge, including spin, orbital and valley et al have manifested themselves to be of the great interests and applicable potentials. Recently, the multipolar degrees of freedom have attracted extensive attention in the electronic correlated effects. In this work, we systematically studied the transport, magnetic and thermodynamic properties of the topological semimetal candidate PrBi in the framework of crystalline electric field theory. Our results demonstrate the Γ 3 non-Kramers doublet as the ground state of Pr 3+ (4f 2 ) ions. This ground state is nonmagnetic but carries a non-zero quadrupolar moment Ô 0 2 , and the latter is inferred to undergo a quadrupolar phase transition below 0.08 K. No obvious quadrupolar Kondo effect can be identified. Ultrahigh-field quantum oscillation measurements confirm PrBi as a semimetal with non-trivial Berry phase and low total carrier density 0.06 /f.u. We discuss the interplay between low carrier density and 4f 2 quadrupolar moment, and ascribe the weak quadrupolar ordering and Kondo effect as consequences of the low carrier density. PrBi, thus, opens a new window to the physics of topology and strongly correlated effect with quadrupolar degrees of freedom in the low-carrier-density limit, evoking the need for a reexamination of the Nozières exhaustion problem in the context of multi-channel Kondo effect.

van der Waals (vdW) Josephson junctions can possibly accelerate the development of an advanced superconducting device that utilizes the unique properties of two-dimensional (2D) transition metal dichalcogenide (TMD) superconductors such as spin− orbit coupling and spin−valley locking. Here, we fabricate vertically stacked NbS 2 /NbS 2 Josephson junctions using a modified all-dry transfer technique and characterize the device performance via systematic low-temperature transport measurements. The experimental results show that the superconducting transition temperature of the NbS 2 /NbS 2 Josephson junction is 5.84 K, and the critical current density reaches 3975 A/cm 2 at 2 K. Moreover, we extract a superconducting energy gap Δ = 0.58 meV, which is considerably smaller than that expected from the single band s-wave Bardeen−Cooper−Schrieffer (BCS) model (Δ = 0.89 meV).

Two-dimensional layered MoS2 has attracted tremendous attention because of its unique physical and chemical properties and promising application prospects. To further expand its applications to areas such as gas sensing, biosensing, drug delivery, and photothermal therapy, surface functionalization has been employed to engineer its properties according to multiple perspectives. Herein, we demonstrate a scalable surface modification method to generate functionalized MoS2 flakes by the step-by-step covalent assembly of lipoic acid (LA) and fluorescein isothiocyanate (FITC) molecules. In our approach, reactive disulfide-containing LA molecules were first chemically bonded to the sulfur vacancies (SVs) of MoS2 surfaces. FITC was then linked to MoS2 through LA by a condensation reaction between the amino group of FITC and the carboxyl group of LA. It was demonstrated that the initial LA functionalization enhanced the electronic mobility via the filling of SVs, and the second-step functionalization with FITC induced electron doping of MoS2. Moreover, the covalent attachment of FITC decorated the PL spectrum of MoS2 with an additional green fluorescence at ∼530 nm. This strategy is a universal route to construct a versatile platform for chemical modification of functional groups and provides new opportunities of controlling the electronic and optical properties of transition-metal dichalcogenides.