Transport properties of VSe₂ monolayers separated by bilayers of BiSe

Abstract

The [(BiSe) 11d ] 1 (VSe 2 ) 1 heterostructure was characterized structurally and electrically to determine the effects of interlayer interaction on the charge density wave (CDW) found in VSe 2 and compared to previously reported [(SnSe) 1.15 ] 1 (VSe 2 ) 1 . Out-of-plane x-ray diffraction scans contain reflections that can be indexed as 00l reflections of a BiSe-VSe 2 supercell. Structure refinement indicates that the VSe 2 layer is very similar structurally to that found in [(SnSe) 1.15 ] 1 (VSe 2 ) 1 . Scanning transmission electron microscopy images show a turbostratically disordered layer structure and the formation of anti-phase boundaries in the BiSe bilayer. The [(BiSe) 11d ] 1 (VSe 2 ) 1 heterostructure is metallic with a negative Hall coefficient, in contrast to the positive Hall coefficient found for [(SnSe) 1.15 ] 1 (VSe 2 ) 1 . The CDW found [(SnSe) 1.15 ] 1 (VSe 2 ) 1 is not present in [(BiSe) 11d ] 1 (VSe 2 ) 1 . This work illustrates the importance of inter constituent interactions in determining the transport properties of single layer films.

Correlation of Reduced Interlayer Charge Transfer with Antiphase Boundary Formation in BixSn1–xSe–NbSe2 Heterostructures

“…The c ‐axis lattice parameters decrease with increasing x until x = 0.50, at which point the repeat unit thickness stays approximately constant with the lattice parameter of the x = 1.0 compound. A previous study of MER‐prepared (Bi x Sn 1– x Se) 1+ δ VSe 2 compounds observed the same trend in c parameter with x , . The total decrease in c ‐axis lattice parameter in the compounds reported here is about 15 pm, the same as that for the VSe 2 ‐containing compounds and the parent end member compounds,, and is likely due to the difference in nominal valence between the Bi(3+) and Sn(2+) cations.…”

Concepts of ferrovalley material and anomalous valley Hall effect

“…It demonstrates that 2H-VSe 2 monolayer could be used in valleytronics well above room temperature. Note that the pristine 1T-phase VSe 2 has been widely studied38394041. However, with the presence of space inversion symmetry, it is definitely not a ferrovalley material.…”

Modifying a charge density wave transition by modulation doping: ferecrystalline compounds ([Sn1−xBixSe]1.15)1(VSe2)1 with 0 ≤ x ≤ 0.66

“…36 Extrapolation of the linear fit to x = 1 results in a c-axis lattice parameter of 1.172(7) nm, which is smaller but close to the observed value of 1.179 nm for ([BiSe] 1+d ) 1 (VSe 2 ) 1 reported previously. 27 The Bi-content and the (Bi + Sn)/V-ratio together with the corresponding c-axis lattice parameters for each sample are given in Table 1.…”

“…This approach to indirect doping with electrons might open a new pathway to optimizing the charge density wave transition for specific applications. However, earlier studies on misfit layer compounds 28,29 and ferecrystals 27,30 containing BiX, with X = S or Se, demonstrated that the behavior of Bi within the compounds depends strongly on structural features as well as the transition metal of the dichalcogenide layer, and no general prediction is possible.…”

“…26 The analogous ([BiSe] 1+d ) 1 (VSe 2 ) 1 ferecrystal was recently reported, which had no charge density wave and a negative Hall coefficient rather than the positive Hall coefficient observed for ([SnSe] 1.15 ) m (VSe 2 ) 1 compounds. 27 The interwoven superstructure of two distinct constituents and the presence of rotational disorder among them provide a unique opportunity for indirect (modulation) doping of the VSe 2 constituent. Partial substitution of the Sn by Bi in ([Sn 1Àx Bi x Se] 1.15 ) 1 (VSe 2 ) 1 should in a simple picture result in electron donation from bismuth into the VSe 2 -layer.…”