Combined effect of site dilution and long-range interactions in the Hubbard model: Towards the design of antiferromagnetic half-metallicity

We investigate the magnetotransport properties of a diluted half-filled one-band Hubbard model with second-nearest-neighbor hopping on a simple cubic lattice, aiming at exploring the possibility of metallicity in diluted antiferromagnetic (AF) systems. Our semiclassical Monte Carlo calculations reveal an AF metallic regime in diluted correlated materials. This unexpected metallic regime naturally leads to a central question: How does the introduction of dilution into an AF material, especially with long-range magnetic interactions, induce metallicity---a feature not commonly associated with AFs? To address this question, we demonstrate that, when the on-site repulsive Hubbard interaction strength is set to zero on a percentage of the sites (site dilution), the insulating state weakens due to percolative conduction among the diluted sites at low temperatures. Remarkably, this occurs without any significant alteration to the underlying long-range AF ordering in the system, thereby providing a pathway to realize AF metals. In addition, we show how the sublattice-dependent hopping can be exploited to engineer spin-polarized half-metallic AFs. Overall, our numerical results collectively provide a basis for understanding the combined effect of site dilution and competing interactions, which will assist in the design of AF metals for future spintronic applications.