Giant Spin Gap and Magnon Localization in the Disordered Heisenberg Antiferromagnet Sr2Ir1-xRuxO4

Abstract

We study the evolution of magnetic excitations in the disordered two-dimensional antiferromagnet Sr2Ir1-xRuxO4. A gigantic magnetic gap greater than 40 meV opens at x = 0.27 and increases with Ru concentration, rendering the dispersive magnetic excitations in Sr2IrO4 almost momentum independent. Up to a Ru concentration of x = 0.77, both experiments and first-principles calculations show the Ir Jeff = 1/2 state remains intact. The magnetic gap arises from the local interaction anisotropy in the proximity of the Ru disorder. Under the coherent potential approximation, we reproduce the experimental magnetic excitations using the disordered Heisenberg antiferromagnetic model with suppressed next-nearest neighbor ferromagnetic coupling.

arXiv comment6 pages, 4 figures

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Cited by in corpus (8)

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• Spin-gap and two-dimensional magnetic excitations in Sr2IrO4
• Magnetic excitations in hole-doped Sr2IrO4: A comparison with electron-doped cuprates
• Overdamped antiferromagnetic strange metal state in Sr${}_3$IrRuO${}_7$
• Spin-orbit excitons and electronic configuration of the $5d^4$ insulator Sr${}_3$Ir${}_2$O${}_7$F${}_2$
• The Future of the Correlated Electron Problem
• Magnetism in artificial Ruddlesden-Popper iridates leveraged by structural distortions