By means of inelastic neutron scattering we investigate finite temperature dynamics in the quantum spin ladder compound (C5H12N)2CuBr4 (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.
@article{arxiv.1806.10392,
title = {$z=2$ Quantum Critical Dynamics in a Spin Ladder},
author = {D. Blosser and V. K. Bhartiya and D. J. Voneshen and A. Zheludev},
journal= {arXiv preprint arXiv:1806.10392},
year = {2018}
}
Comments
Minor corrections, extension of supplemental material