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arXiv · 1812.08682

Critical fluctuations in the spin-orbit Mott insulator Sr$_3$Ir$_2$O$_7$

J. G. Vale·S. Boseggia·H. C. Walker·R. S. Springell·E. C. Hunter·R. S. Perry·S. P. Collins·D. F. McMorrow
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Abstract

X-ray magnetic critical scattering measurements and specific heat measurements were performed on the perovskite iridate Sr$_3$Ir$_2$O$_7$. We find that the magnetic interactions close to the N\'{e}el temperature $T_N$ = 283.4(2) K are three-dimensional. This contrasts with previous studies which suggest two-dimensional behaviour like Sr$_2$IrO$_4$. Violation of the Harris criterion ($d\nu>2$) means that weak disorder becomes relevant. This leads a rounding of the antiferromagnetic phase transition at $T_N$, and modifies the critical exponents relative to the clean system. Specifically, we determine that the critical behaviour of Sr$_3$Ir$_2$O$_7$ is representative of the diluted 3D Ising universality class.

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J. G. Vale, S. Boseggia, H. C. Walker, R. S. Springell, E. C. Hunter, R. S. Perry, S. P. Collins, D. F. McMorrow. 2018-12-20. Critical fluctuations in the spin-orbit Mott insulator Sr$_3$Ir$_2$O$_7$. https://doi.org/10.1088/1361-648x/ab0471

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