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arXiv · 1702.05273

Novel Crossover in Coupled Spin Ladders

M. Jeong·H. Mayaffre·C. Berthier·D. Schmidiger·A. Zheludev·M. Horvatić
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Abstract

We report a novel crossover behavior in the long-range-ordered phase of a prototypical spin-$1/2$ Heisenberg antiferromagnetic ladder compound $\mathrm{(C_7H_{10}N)_2CuBr_4}$. The staggered order was previously evidenced from a continuous and symmetric splitting of $^{14}$N NMR spectral lines on lowering temperature below $T_c\simeq 330$ mK, with a saturation towards $\simeq 150$ mK. Unexpectedly, the split lines begin to further separate away below $T^*\sim 100$ mK while the line width and shape remain completely invariable. This crossover behavior is further corroborated by the NMR relaxation rate $T_1^{-1}$ measurements. A very strong suppression reflecting the ordering, $T_1^{-1}\sim T^{5.5}$, observed above $T^*$, is replaced by $T_1^{-1}\sim T$ below $T^*$. These original NMR features are indicative of unconventional nature of the crossover, which may arise from a unique arrangement of the ladders into a spatially anisotropic and frustrated coupling network.

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M. Jeong, H. Mayaffre, C. Berthier, D. Schmidiger, A. Zheludev, M. Horvatić. 2017-02-17. Novel Crossover in Coupled Spin Ladders. https://doi.org/10.1103/physrevlett.118.167206

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