Structural and Optical Properties of Single- and Few-Layer Magnetic Semiconductor CrPS₄

Abstract

Atomically thin binary two-dimensional (2D) semiconductors exhibit diverse physical properties depending on their composition, structure, and thickness. By adding another element in these materials, which will lead to formation of ternary 2D materials, the property and structure would greatly change and significantly expanded applications could be explored. In this work, we report structural and optical properties of atomically thin chromium thiophosphate (CrPS), a ternary antiferromagnetic semiconductor. Its structural details were revealed by X-ray and electron diffraction. Transmission electron microscopy showed that preferentially cleaved edges are parallel to diagonal Cr atom rows, which readily identified their crystallographic orientations. Strong in-plane optical anisotropy induced birefringence that also enabled efficient determination of crystallographic orientation using polarized microscopy. The lattice vibrations were probed by Raman spectroscopy and exhibited significant dependence on thickness of crystals exfoliated down to a single layer. Optical absorption determined by reflectance contrast was dominated by d-d-type transitions localized at Cr ions, which was also responsible for the major photoluminescence peak at 1.31 eV. The spectral features in the absorption and emission spectra exhibited noticeable thickness dependence and hinted at a high photochemical activity for single-layer CrPS. The current structural and optical investigation will provide a firm basis for future study and application of this kind of atomically thin magnetic semiconductors.

Metal Phosphorous Trichalcogenides (MPCh3): From Synthesis to Contemporary Energy Challenges

“…Apart from conductivity improvement, there is the possibility of charge transfer between rGO and FePSe 3 as observed from the downfield shift of the Fe 2p peak in high-resolution XPS data of the composite (Figure 3b). [43] Owing to the interesting 2D anisotropic behavior of MPCh 3 , [21,[25][26][27]31,44,50] they have potential application in lowdimensional magnetic and spintronic devices.E xperimental studies and theoretical calculations of the magnetic properties of MPCh 3 have been widely performed. In the past, the most studied MPCh 3 compounds have been FePS 3 ,M nPS 3 ,a nd NiPS 3 , [13] with the main focus on the bulk crystal of MPCh 3 , [21,26,27,38] whereas the theoretical calculations of the spin-state were concentrated on MPCh 3 monolayers.…”

“…Forl arge-scale exfoliation, ball milling or liquid phase exfoliation methods in various solvents,s uch as NMP and DMF,h ave been reported. [40][41][42][43][44][45][46][47] Using such methods usually induces higher degree of impurities and defective edge sites. Although such methods are not ideal for photo-electronic-based devices,i nt he field of electrochemical catalysts,i fc ontrolled, these can have enhanced effects in the catalytic activity of exfoliated MPCh 3 .…”

Lanthanide orthothiophosphates revisited: single-crystal X-ray, Raman, and DFT studies of TmPS4 and YbPS4

“…Additionally, they are studied as materials for next-generation digital electronics due to antiferromagnetic semiconducting properties in some layered compounds (e.g. CrPS 4 [17]). Interest in this family of compounds increased further when first principles and experimental investigations showed their potential for applications in nonlinear optics, in particular for mid infrared coherent light generation [18].…”

Exfoliated Layered Manganese Trichalcogenide Phosphite (MnPX3, X = S, Se) as Electrocatalytic van der Waals Materials for Hydrogen Evolution

“…Such exfoliated materials have excellent quality for the basic research of physical properties; however, the scalability of such procedures is very limited. For large‐scale exfoliation, ball milling or liquid phase exfoliation methods in various solvents, such as 1‐methylpyrrolidin‐2‐one (NMP) and N , N ‐dimethylmethanamide (DMF), have been reported . Using such methods usually induces higher degree of impurities and defective edge sites.…”