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arXiv · 1707.05243

Finite-temperature correlations in a quantum spin chain near saturation

Dominic Blosser·Noam Kestin·Kirill Yu. Povarov·Robert Bewley·Emanuele Coira·Thierry Giamarchi·Andrey Zheludev
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Abstract

Inelastic neutron-scattering and finite-temperature density matrix renormalization group (DMRG) calculations are used to investigate the spin excitation spectrum of the $S=1/2$ Heisenberg spin chain compound K$_2$CuSO$_4$Cl$_2$ at several temperatures in a magnetic field near saturation. Critical correlations characteristic of the predicted $z=2$, $d=1$ quantum phase transition occurring at saturation are shown to be consistent with the observed neutron spectra. The data is well described with a scaling function computed using a free fermion description of the spins, valid close to saturation, and the corresponding scaling limits. One of the most prominent non-universal spectral features of the data is a novel thermally activated longitudinal mode that remains underdamped across most of the Brillouin zone.

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Dominic Blosser, Noam Kestin, Kirill Yu. Povarov, Robert Bewley, Emanuele Coira, Thierry Giamarchi, Andrey Zheludev. 2017-10-02. Finite-temperature correlations in a quantum spin chain near saturation. https://doi.org/10.1103/physrevb.96.134406

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