Phonon-Mediated Superconductivity versus Topological Surface States in Pressure-Tuned Heavy-Fermion Compounds: A Comparative Transport and Spectroscopic Evaluation

Abstract

The interplay between phonon-mediated Cooper pairing and topologically protected surface states in heavy-fermion compounds under hydrostatic pressure remains a central unresolved problem in condensed matter physics. This study presents a systematic comparison of two competing theoretical frameworks—conventional BCS electron–phonon coupling and topological Kondo insulator models—applied to CeB₆ and SmB₆ under pressures ranging from 0.1 to 18 GPa. Employing angle-resolved photoemission spectroscopy (ARPES), low-temperature magnetotransport, and ab initio density functional perturbation theory calculations, we demonstrate that neither framework alone adequately captures the observed Fermi surface reconstructions below 4 K. A hybridized model incorporating spin–orbit entanglement is proposed, yielding a 17% improvement in quasiparticle lifetime predictions and resolving previously anomalous Hall conductance plateaus.