Two-dimensional heisenberg behavior of J eff=1/2 isospins in the paramagnetic state of the spin-orbital mott insulator Sr 2IrO 4

S. Fujiyama, H. Ohsumi, T. Komesu, J. Matsuno, B. J. Kim, M. Takata, T. Arima, H. Takagi

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139 Citations (Scopus)

Abstract

The dynamical correlations of J eff=1/2 isospins in the paramagnetic state of spin-orbital Mott insulator Sr 2IrO 4 were revealed by resonant magnetic x-ray diffuse scattering. We found a two-dimensional antiferromagnetic fluctuation with a large in-plane correlation length exceeding 100 lattice spacings at even 20 K above the magnetic ordering temperature. In marked contrast to the naive expectation of the strong magnetic anisotropy associated with an enhanced spin-orbit coupling, we discovered an isotropic isospin correlation that is well described by the two-dimensional S=1/2 quantum Heisenberg model. The estimated antiferromagnetic coupling constant as large as J∼0.1eV that is comparable to the small Mott gap (<0.5eV) points out the weak and marginal Mott character of this spin-orbital entangled system.

Original languageEnglish
Article number247212
JournalPhysical review letters
Volume108
Issue number24
DOIs
Publication statusPublished - 2012 Jun 15
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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