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arXiv · 1806.10392

$z=2$ Quantum Critical Dynamics in a Spin Ladder

D. Blosser·V. K. Bhartiya·D. J. Voneshen·A. Zheludev
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Abstract

By means of inelastic neutron scattering we investigate finite temperature dynamics in the quantum spin ladder compound (C$_5$H$_{12}$N)$_2$CuBr$_4$ (BPCB) near the magnetic field induced quantum critical point with dynamical exponent $z=2$. We observe universal finite-temperature scaling of the transverse local dynamic structure factor in spectacular quantitative agreement with long-standing theoretical predictions. At the same time, already at rather low temperatures, we observe strong non-universal longitudinal fluctuations. To separate the two, we make use of an intrinsic leg-exchange symmetry of the spin ladder. Complementary measurements of specific heat also reveal striking scaling behavior near the quantum critical point.

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D. Blosser, V. K. Bhartiya, D. J. Voneshen, A. Zheludev. 2018-12-27. $z=2$ Quantum Critical Dynamics in a Spin Ladder. https://doi.org/10.1103/physrevlett.121.247201

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