Experimental determination of surface thermal expansion and electron–phonon coupling constant of 1T-PtTe₂

Abstract

We report an extensive structural characterization of the surface of 1T-PtTe2 crystals by means of helium atom scattering (HAS) and ultra-high resolution scanning tunnelling microscopy (STM). HAS reveals that this bi-dimensional surface presents a large structural corrugation (∼) in direction. The surface lattice constant of PtTe2 derived from the positions of the helium diffraction peaks up to fifth order was found to be , in agreement with STM and x-ray diffraction measurements. This value remains unchanged in the temperature range between 90 and 580 K. These findings suggest that 1T-PtTe2 behaves similarly to graphene on a weakly-interacting substrate, for which the surface thermal expansion coefficient is zero within experimental error. The electron–phonon coupling constant has been determined by recording the thermal attenuation of the elastic diffraction peaks of PtTe2. Based on a recently developed quantum theoretical method adapted to layered degenerate semiconductors we find that lies between 0.38–0.42.

Imaging and identification of point defects in PtTe2

“…1d). The sharp peaks observed are indicative of good crystallinity in the film, and are in agreement with previous reports 11,18,40,41 . SEM images of the PtTe 2 film show its polycrystalline nature with grains ranging between 200 and 400 nm in size (see Supplementary Fig.…”

“…1c), confirming the 1 T crystal structure of the PtTe 2 grains. An average lattice constant and a layer step height for the PtTe 2 of 4.0 ± 0.03 and 5.1 ± 0.06 Å, respectively, were determined from the atomically resolved surface, which is in agreement with our simulated results and previous experimental reports 40,41 . Considering this, we estimate from STM that the thickness of the flakes in our measurements ranged from 30 to 50 layers.…”

Surface electronic corrugation of a one-dimensional topological metal: Bi(114)

“…Earlier works showed that the position of the rainbow angle in a diffraction scan gives an estimate for the corrugation height of a surface. [49][50][51] In fact, a peak-to-peak corrugation of about 0.5 Å yields a rainbow angle of 6.2 • and would thus be consistent with 205 the high intensities of the (03) diffraction peaks in Figure 3(a). However, the simple assumptions made above do neither hold for the herein used scattering geometry nor the asymmetry of the surface corrugation.…”

Measuring the Electron–Phonon Interaction in Two-Dimensional Superconductors with He-Atom Scattering

“…Considering the superior resolution of inelastic HAS spectroscopy in the meV range with respect to IXS, and its ability to obtain direct information on e-ph coupling constants, revisiting with HAS the CDW phases and transitions in this class of 2D superconductors would be highly desirable. Recent examples in this direction are the HAS measurements of λ in 2H-MoS2 [12], 1T-PtTe2 [13] and 1T-PdTe2 [86]. [71].…”