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DOE OSTI · 1845606

Antiferromagnetic excitonic insulator state in Sr3Ir2O7

Mazzone, D. G. (ORCID:0000000204210625)·Shen, Y.·Suwa, H. (ORCID:0000000260262630)·Fabbris, G. (ORCID:0000000182784985)·Yang, J.·Zhang, S. -S.·Miao, H. (ORCID:0000000310785713)·Sears, J.·Jia, Ke·Shi, Y. G.·Upton, M. H.·Casa, D. M.·Liu, X.·Liu, Jian (ORCID:0000000179622547)·Batista, C. D. (ORCID:0000000316673667)·Dean, M. P. M. (ORCID:0000000151393543)
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Abstract

Abstract Excitonic insulators are usually considered to form via the condensation of a soft charge mode of bound electron-hole pairs. This, however, presumes that the soft exciton is of spin-singlet character. Early theoretical considerations have also predicted a very distinct scenario, in which the condensation of magnetic excitons results in an antiferromagnetic excitonic insulator state. Here we report resonant inelastic x-ray scattering (RIXS) measurements of Sr 3 Ir 2 O 7 . By isolating the longitudinal component of the spectra, we identify a magnetic mode that is well-defined at the magnetic and structural Brillouin zone centers, but which merges with the electronic continuum in between these high symmetry points and which decays upon heating concurrent with a decrease in the material’s resistivity. We show that a bilayer Hubbard model, in which electron-hole pairs are bound by exchange interactions, consistently explains all the electronic and magnetic properties of Sr 3 Ir 2 O 7 indicating that this material is a realization of the long-predicted antiferromagnetic excitonic insulator phase.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYelectronic materialselectronic propertiesmagnetic materialsmagnetic properties

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Mazzone, D. G. (ORCID:0000000204210625), Shen, Y., Suwa, H. (ORCID:0000000260262630), Fabbris, G. (ORCID:0000000182784985), Yang, J., Zhang, S. -S., Miao, H. (ORCID:0000000310785713), Sears, J., Jia, Ke, Shi, Y. G., Upton, M. H., Casa, D. M., Liu, X., Liu, Jian (ORCID:0000000179622547), Batista, C. D. (ORCID:0000000316673667), Dean, M. P. M. (ORCID:0000000151393543). 2022-02-17. Antiferromagnetic excitonic insulator state in Sr3Ir2O7. https://doi.org/10.1038/s41467-022-28207-w

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