Exploring Native Atomic Defects in NiTe2

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

“…This defect, labeled as type C, changes drastically its appearance as a function of the sample voltage, showing up as a bright protrusion at unoccupied states and a dark ring at occupied states. Finally, an additional defect (figure 2(g)) is also found although much less abundant, type D. Surprisingly, we did not observe Te vacancies, in contrast to previous works on PtTe 2 crystals [27] and other TMDs [24,51] where they are resolved as depressions at Te-terminated surfaces. We attribute this to the different growth process used in our work.…”

“…Similar defects were previously reported in other transition metal chalcogenides (TMCs), i.e. PtSe 2 [26], NiTe 2 [24] and MnBi 2 Te 4 [31], and attributed to vacancies or chalcogen substitutions in the first metallic layer of the TMCs. The second most frequently observed defect is the type B (figure 2(e)), with an incidence of 6.90 × 10 11 cm −2 .…”

“…A sixfold symmetry in these kind of systems has been attributed to a warping of the state [53][54][55] or an anisotropic scattering from a non-circular defect [56]. In TMDs, it was shown that the predominant defects are diffuse triangles [24,26,27,31,51,55,57]. In this case, the size and the shape of defects result in anisotropic waves with short wavelengths, evident from the inspection of QPI maps in figure 4(a).…”

“…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 .…”