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arXiv · 1110.0806

Disorder instability of the magnon condensate in a frustrated spin ladder

E. Wulf·S. Mühlbauer·T. Yankova·A. Zheludev
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Abstract

The effect of disorder is studied on the field-induced quantum phase transition in the frustrated spin-ladder compound H8C4SO2Cu2(Cl[1-x]Brx)4 using bulk magnetic and thermodynamic measurements. The parent material (x=0) is a quantum spin liquid, which in applied fields is known to form a magnon condensate with long-range helimagnetic order. We show that bond randomness introduced by a chemical substitution on the non-magnetic halogene site destroys this phase transition at very low concentrations, already for x=0.01. The extreme fragility of the magnon condensate is attributed to random frustration in the incommensurate state.

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E. Wulf, S. Mühlbauer, T. Yankova, A. Zheludev. 2011-10-04. Disorder instability of the magnon condensate in a frustrated spin ladder. https://doi.org/10.1103/physrevb.84.174414

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