Finite-temperature correlations in a quantum spin chain near saturation

D. Blosser, N. Kestin, K. Yu. Povarov, R. Bewley, E. Coira, T. Giamarchi, and A. Zheludev
Phys. Rev. B 96, 134406 – Published 3 October 2017

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 K2CuSO4Cl2 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 nonuniversal 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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  • Received 18 July 2017

DOI:https://doi.org/10.1103/PhysRevB.96.134406

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

D. Blosser1,*, N. Kestin2, K. Yu. Povarov1, R. Bewley3, E. Coira2, T. Giamarchi2, and A. Zheludev1,†

  • 1Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich, Switzerland
  • 2Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest Ansermet, 1211 Geneva, Switzerland
  • 3ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, United Kingdom

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Vol. 96, Iss. 13 — 1 October 2017

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