Seminarium Fizyki Materii Skondensowanej

In my talk, I show how a single microscopic electronic model – the two-orbital Hubbard–Kanamori chain – unifies three central themes of correlated quantum matter: resonating-valence-bond (RVB) physics, pseudogaps, and superconducting tendencies. At half-filling, increasing Hubbard and Hund interactions drives a sharp transition from a trivial phase to a topological state with zero-energy edge modes. Although this phase is related to the S=1 Heisenberg chain in the strong-coupling limit (closely resembling the Affleck–Kennedy–Lieb–Tasaki state), its topological character emerges already at moderate interactions, before fully developed local moments form. From an electronic perspective, the resulting state is naturally interpreted as a gapped RVB phase, characterized by short-range valence bonds, a finite spin gap, and fractionalized excitations. Upon doping, mobile charge carriers propagate in this correlated singlet background, promoting the binding of holes into Cooper pairs through the underlying valence-bond correlations. In this regime, the system exhibits a nontrivial coexistence of collective modes: coherent magnon excitations inherited from the parent Haldane phase persist at long wavelengths, while fractionalized spinon-like excitations contribute to the high-energy and short-distance spin response. This multi-scale structure of the spin dynamics is accompanied by a suppression of low-energy spectral weight in the single-particle sector, leading to pseudogap features that naturally arise from the interplay between pairing correlations and magnetic fluctuations.