Electron–phonon coupling in lightly [formula omitted]-doped 1T monolayers of PdSTe and PdSeTe: A rigid band approximation approach

Abstract

In this paper, we present a preliminary study to determine the electron–phonon (el–ph) coupling in Janus 1T monolayered PdSTe and PdSeTe within the rigid band approximation (RBA). Under the assumption that both electronic band structures and phonon dispersions remain intact, or suffer slight changes at most, the Fermi energy is manually shifted towards the conduction bands. Without spin–orbit coupling (SOC), these structures are predicted to be semiconductors with electronic bandgaps of 0.33 eV for PdSTe and 0.34 eV for PdSeTe and with an insignificant electron–phonon coupling. We find that minimal small Fermi energy shifts of the order of 35 meV and 65 meV applied to 1T PdSTe and PdSeTe respectively, are sufficient to produce non-zero values of λ in both systems. These shifts could physically correspond to small electron doping of the materials, not exceeding 4%. Our calculations give that λ=1.77 and λ=0.5 for PdSTe and PdSeTe respectively. The corresponding lowest superconducting temperatures (Tc) register 0.28 K for PdSeTe and 28.19 K for PdSTe. We also demonstrate that the longitudinal optical and acoustical phonon modes may play a key role in the process of superconductivity of the doped materials. The above temperature of PdSTe is larger than those for 2D borophene, stanene, phosophorene and arsenene indicating that, in principle if the right dopant is found, lightly n-doped PdSTe could be promising in the area of 2D superconductors.