Distinctive electron localization on the surface of two-dimensional antiferromagnetic metal PdCrO₂

Electron localization is a focal topic in condensed matter physics. In materials where electrons couple with lattice/spin degrees of freedom, an accurate characterization of electron localization would not only advance our understanding of correlated electron systems but also hold potential as a key to unraveling the long-standing puzzle of high-temperature superconductivity. Here, utilizing angle-resolved photoemission spectroscopy (ARPES), we reveal an electron localization that occurs on the surface of a two-dimensional antiferromagnetic metal PdCrO₂. Various characteristics of electron localization were observed, including quasiparticle mass renormalization, the “waterfall” feature, high-energy incoherent states, and a pseudogap. We find that the energy scale of band renormalization is highly correlated with the mode coupling energy observed in the metallic state, suggesting that the localization behavior can be explained by polaron localization driven by an enhancement of the coupling between electrons and lattice/spin excitations. Our data highlight phenomena that emerge universally in complex correlated systems where electrons couple with lattice/spin excitations. This provides experimental validation for various theoretical models of delocalized correlated systems. Our results also demonstrate that the coupling strength can be tuned continuously on the surface of PdCrO₂, making it a model system for investigating exotic phenomena in complex correlated materials.