Abstract
The magnetic critical scattering in has been characterized using x-ray resonant magnetic scattering (XRMS) both below and above the three-dimensional antiferromagnetic ordering temperature . The order parameter critical exponent below is found to be , in the range of the two-dimensional (2D) universality class. Over an extended temperature range above , the amplitude and correlation length of the intrinsic critical fluctuations are well described by the 2D Heisenberg model with anisotropy. This contrasts with an earlier study of the critical scattering over a more limited range of temperature, which found agreement with the theory of the isotropic 2D Heisenberg quantum antiferromagnet, developed to describe the critical fluctuations of the conventional Mott insulator and related systems. Our study therefore establishes the importance of anisotropy in the low-energy effective Hamiltonian of , the prototypical spin-orbit Mott insulator.
- Received 23 December 2014
- Revised 22 April 2015
DOI:https://doi.org/10.1103/PhysRevB.92.020406
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