Thallium-doped lead telluride (PbTe:Tl) exhibits thermoelectric transport anomalies that remain unexplained by conventional phonon-drag and band-structure models. This work demonstrates that these anomalies are consistent with Migdal-type non-adiabatic electron-phonon coupling arising from resonant impurity states near the Fermi level. Analysis of existing experimental literature reveals three key signatures: (1) non-monotonic Seebeck coefficient with peak enhancement at T ≈ 250 K, (2) anomalous suppression of lattice thermal conductivity beyond alloy-scattering predictions, and (3) failure of standard parabolic-band thermopower models. Using the Migdal-Eliashberg framework, I derive quantitative predictions including longitudinal optical (LO) phonon softening (Δω/ω ≈ 10–20% at 2–5 THz), magnetic-field-dependent Seebeck suppression (ΔS/S ≈ 5–10% at B = 5 T), and mass enhancement observable in angle-resolved photoemission spectroscopy (λ ≈ 1.5–2.0). These predictions are testable with existing experimental techniques. Validation would establish PbTe:Tl as the first confirmed Migdal-enhanced thermoelectric material and enable systematic design of non-adiabatic transport systems for energy conversion applications.
Francis Procaccia (Tue,) studied this question.