Controlling Spin-Orbit Coupling to Tailor Type-II Dirac Bands.

NiTe, a type-II Dirac semimetal with a strongly tilted Dirac band, has been explored extensively to understand its intriguing topological properties. Here, using density functional theory calculations, we report that the strength of the spin-orbit coupling (SOC) in NiTe can be tuned by Se substitution. This results in negative shifts of the bulk Dirac point (BDP) while preserving the type-II Dirac band.

Multiple charge density wave phases of monolayer VSemanifested by graphene substrates.

A combined study of scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES) is conducted to understand the multiple charge density wave (CDW) phases of monolayer (ML) VSefilms manifested by graphene substrates. Submonolayer (∼0.8 ML) VSefilms are prepared on two different substrates of single-layer graphene (SLG) and bi-layer graphene (BLG) on a 6H-SiC(0001).

Novel polymorphic phase of two-dimensional VSe: the 1T' structure and its lattice dynamics.

Polymorphisms allowing multiple structural phases are among the most fascinating properties of transition metal dichalcogenides (TMDs). Herein, the polymorphic 1T' phase and its lattice dynamics for bilayer VSe grown on epitaxial bilayer graphene are investigated via low temperature scanning tunneling microscopy (STM). The 1T' structure, mostly observed in group-6 TMDs, is unexpected in VSe, which is a group-5 TMD.

Emergence of a Metal-Insulator Transition and High-Temperature Charge-Density Waves in VSe at the Monolayer Limit.

Emergent phenomena driven by electronic reconstructions in oxide heterostructures have been intensively discussed. However, the role of these phenomena in shaping the electronic properties in van der Waals heterointerfaces has hitherto not been established. By reducing the material thickness and forming a heterointerface, we find two types of charge-ordering transitions in monolayer VSe on graphene substrates.

Atomistic study of the alloying behavior of crystalline SnSeS.

Recently, layered chalcogenide alloys (LCAs) have been extensively investigated for use in various practical applications by selectively controlling the amount of foreign components. However, the alloying behavior of layered chalcogenides has been rarely explored at the atomistic level. Here, we study the microstructural evolution of SnSeS alloys on the atomic scale by combining scanning tunneling microscopy (STM) measurements with first-principles density functional theory (DFT) calculations.

Achieving ZT=2.2 with Bi-doped n-type SnSe single crystals.

Recently SnSe, a layered chalcogenide material, has attracted a great deal of attention for its excellent p-type thermoelectric property showing a remarkable ZT value of 2.6 at 923 K. For thermoelectric device applications, it is necessary to have n-type materials with comparable ZT value.