Publication

Importance of XY anisotropy in Sr2IrO4 revealed by magnetic critical scattering experiments

Henrik Moodysson Rønnow
2015
Journal Articles

Abstract

The magnetic critical scattering in Sr2IrO4 has been characterized using x-ray resonant magnetic scattering (XRMS) both below and above the three-dimensional antiferromagnetic ordering temperature T-N. The order parameter critical exponent below TN is found to be beta = 0.195(4), in the range of the two-dimensional (2D) XYh(4) universality class. Over an extended temperature range above TN, the amplitude and correlation length of the intrinsic critical fluctuations are well described by the 2D Heisenberg model with XY 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 La2CuO4 and related systems. Our study therefore establishes the importance of XY anisotropy in the low-energy effective Hamiltonian of Sr2IrO4, the prototypical spin-orbit Mott insulator.

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Henrik Moodysson Rønnow
2015
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/f84f1362-de61-4eff-83e6-0363e9d309a7

About this result

Related concepts (22)

Critical exponent

Critical exponents describe the behavior of physical quantities near continuous phase transitions. It is believed, though not proven, that they are universal, i.e. they do not depend on the details of the physical system, but only on some of its general features. For instance, for ferromagnetic systems, the critical exponents depend only on: the dimension of the system the range of the interaction the spin dimension These properties of critical exponents are supported by experimental data.

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