Edge and Point‐Defect Induced Electronic and Magnetic Properties in Monolayer PtSe₂

Abstract

Edges and point defects in layered dichalcogenides are important for tuning their electronic and magnetic properties. By combining scanning tunneling microscopy (STM) with density functional theory (DFT), the electronic structure of edges and point defects in 2D-PtSe 2 are investigated where the 1.8 eV bandgap of monolayer PtSe 2 facilitates the detailed characterization of defect-induced gap states by STM. The stoichiometric zigzag edge terminations are found to be energetically favored. STM and DFT show that these edges exhibit metallic 1D states with spin polarized bands. Various native point defects in PtSe 2 are also characterized by STM. A comparison of the experiment with simulated images enables identification of Se-vacancies, Pt-vacancies, and Se-antisites as the dominant defects in PtSe 2 . In contrast to Se-or Pt-vacancies, the Se-antisites are almost devoid of gap states. Pt-vacancies exhibit defect induced states that are spin polarized, emphasizing their importance for inducing magnetism in PtSe 2 . The atomic-scale insights into defect-induced electronic states in monolayer PtSe 2 provide the fundamental underpinning for defect engineering of PtSe 2 -monolayers and the newly identified spin-polarized edge states offer prospects for engineering magnetic properties in PtSe 2 nanoribbons.

Atomic-scale study of type-II Dirac semimetal PtTe2 surface

“…Evidences of strongly tilted Dirac cones and closed Fermi surfaces were confirmed in these systems by angle-resolved photoemission spectroscopy [14][15][16][17][18][19][20] and transport measurements [21][22][23]. Complementary, scanning tunneling microscopy (STM) enables the direct visualization of their surface structure including native defects [24][25][26][27][28]. Typical native defects in TMDs are vacancies, interstitial impurities and substitutional impurities.…”

“…These calculations were performed using a = 4.01 Å and c = 5.06 Å. Although previous measurements and calcultions were reported for parental compounds [24][25][26][27]52], a clear identification of the defects is still lacking. Interestingly, by performing a large number of simulations for different defects and comparing them with the STM measurements, we can unequivocally identify the defects present in PtTe 2 .…”

Effect of the crystallographic c-axis orientation on the tribological properties of the few-layer PtSe2

“…A small difference in the adhesion and friction signal for the films with VA and HA PtSe 2 flakes, especially at low applied load, could indicate that the type of the termination of the flake edges (type of atoms or their groups [46]) has an effect on the tribological properties of the films at the nanoscale. In particular, the PtSe 2 flakes have 1T coordination, which results in the formation of the edges with predominant chalcogen atoms termination [47]. In contrast, the H-phase metallic edges termination is preferable in MoS 2 layers [47].…”

“…In particular, the PtSe 2 flakes have 1T coordination, which results in the formation of the edges with predominant chalcogen atoms termination [47]. In contrast, the H-phase metallic edges termination is preferable in MoS 2 layers [47]. Therefore, Se atoms termination of the PtSe 2 edges and basal plane can produce similar tribological behaviour for the films with different orientations.…”

Controlling Stoichiometry in Ultrathin van der Waals Films: PtTe2, Pt2Te3, Pt3Te4, and Pt2Te2

“…Thus, Te vacancies cannot be annihilated by phase transformation and must remain as vacancies. Point defects in Pt-dichalcogenides have been studied extensively, and Pt vacancies have been identified as the locus of magnetic moments . In the case of Pt 2 Te 2 , the DFT simulations do not exhibit spin-polarized states, as shown in Figure S9, and thus are unlikely to exhibit magnetic properties.…”