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arXiv · 1201.6143

Field-induced criticality in a gapped quantum magnet with bond disorder

D. Hüvonen·S. Zhao·M. Månsson·T. Yankova·E. Ressouche·C. Niedermayer·M. Laver·S. N. Gvasaliya·A. Zheludev
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Abstract

Neutron diffraction and calorimetric measurements are used to study the field-induced quantum phase transition in piperazinium-Cu$_2$(Cl$_{1-x}$Br$_x$)$_6$ ($x=0$, x=3.5% and x=7.5%), a prototypical quantum antiferromagnet with random bonds. The critical indexes $ϕ$ and $β$ are determined. The findings contradict some original predictions for Bose Glass based on the assumption $z=d$, but are consistent with recent theoretical results implying $z<d$. Inelastic neutron experiments reveal that disorder has a profound effect on the lowest-energy magnetic gap excitation in the system.

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D. Hüvonen, S. Zhao, M. Månsson, T. Yankova, E. Ressouche, C. Niedermayer, M. Laver, S. N. Gvasaliya, A. Zheludev. 2012-03-13. Field-induced criticality in a gapped quantum magnet with bond disorder. https://doi.org/10.1103/physrevb.85.100410

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