Antiferromagnetic excitonic insulator state in Sr3Ir2O7

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 th...

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Bibliographic Details
Published in:	Nature communications 2022-02, Vol.13 (1), p.913-913, Article 913
Main Authors:	Mazzone, D. G., Shen, Y., Suwa, H., Fabbris, G., Yang, J., Zhang, S.-S., Miao, H., Sears, J., Jia, Ke, Shi, Y. G., Upton, M. H., Casa, D. M., Liu, X., Liu, Jian, Batista, C. D., Dean, M. P. M.
Format:	Article
Language:	eng
Subjects:	Antiferromagnetism Brillouin zones Condensates Electrons Excitons Holes (electron deficiencies) Inelastic scattering Insulators Magnetic properties X ray scattering
Online Access:	Get full text
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Summary:	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.
ISSN:	2041-1723 2041-1723