Kinetically-Driven Frustration in Hybrid Spin Ladders

We introduce a spin ladder model incorporating localized and delocalized spins, which is exactly solvable using the decoration-iteration and transfer-matrix techniques. Quantum correlations between delocalized spins induce an antiferromagnetic coupling between the spin chains that competes with a direct ferromagnetic exchange coupling. A resulting kinetically-driven frustration is predominant in the regime of low temperatures and large hopping amplitudes. We provide the full ground-state phase diagram, as well as the frustration diagram on distinct coupling regimes.