Combine effect of site dilution and long-range interaction on magnetic and transport properties in the half-filled Hubbard model

TL;DR

This paper explores how site dilution and long-range interactions in a half-filled Hubbard model can induce metallicity in antiferromagnetic systems, revealing pathways for designing antiferromagnetic metals for spintronics.

Contribution

It demonstrates that site dilution weakens insulating states without disrupting antiferromagnetic order, enabling the realization of antiferromagnetic metals with potential spintronic applications.

Findings

Dilution induces percolative conduction at low temperatures.

Long-range interactions maintain antiferromagnetic order despite dilution.

Hopping engineering can produce spin-polarized half-metallic antiferromagnets.

Abstract

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 to explore the possibility of metallicity in diluted antiferromagnetic systems. Our semiclassical Monte Carlo calculations reveal an antiferromagnetic metallic regime in diluted correlated materials. This unexpected metallic regime naturally leads to a central question: how does the introduction of dilution into an antiferromagnetic material, especially with long-range magnetic interactions, induce metallicity -- a feature not commonly associated with antiferromagnets? 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 antiferromagnetic ordering in the system, thereby providing a pathway to realize antiferromagnetic metals. In addition, we show how the sublattice-dependent hopping can be exploited to engineer spin-polarized half-metallic antiferromagnets. 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 new antiferromagnetic metals for future spintronic applications.