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 language | English |
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Article number | 247212 |
Journal | Physical review letters |
Volume | 108 |
Issue number | 24 |
DOIs | |
Publication status | Published - 2012 Jun 15 |
Externally published | Yes |
ASJC Scopus subject areas
- Physics and Astronomy(all)