ESR modes in a Strong-Leg Ladder in the Tomonaga-Luttinger Liquid Phase

ORAL

Abstract

Magnetic excitations in the strong-leg quantum spin ladder compound (C$_7$H$_{10}$N)$_2$CuBr$_4$ (known as DIMPY) in the field-induced Tomonaga-Luttinger spin liquid phase are studied by means of high-field electron spin resonance (ESR) spectroscopy. The presence of a gapped ESR mode with unusual non-linear frequency-field dependence is revealed experimentally. Using a combination of analytic and exact diagonalization methods, we compute the dynamical structure factor and identify this mode with longitudinal excitations in the antisymmetric channel. We argue that these excitations constitute a fingerprint of the spin dynamics in a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder and owe its ESR observability to the uniform Dzyaloshinskii-Moriya interaction.

*This work was partially supported by the DFG and Helmholtz Gemeinschaft (Germany), Swiss SNF under Division II, and ERC synergy UQUAM project. We acknowledge the support of the HLD at HZDR, member of the European Magnetic Field Laboratory (EMFL).

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Authors

  • S. Zvyagin

    • HLD-HZDR, D-01328 Dresden, Germany

  • M. Ozerov

    • Radboud University, 6525 ED Nijmegen, The Netherlands

  • M. Maksymenko

    • Weizmann Institute of Science
    • Weizmann Institute of Science, Rehovot 76100, Israel

  • J. Wosnitza

    • HLD-HZDR, D-01328 Dresden, Germany

  • Andreas Honecker

    • Universit\'e de Cergy-Pontoise, F-95302 Cergy-Pontoise Cedex, France
    • LPTM, Universit\'e de Cergy-Pontoise

  • Christopher Landee

    • Clark University, Worcester, MA 01060, USA
    • Clark University
    • Department of Physics, Clark University

  • M. Turnbull

    • Clark University, Worcester, MA 01060, USA

  • S.C. Furuya

    • University of Geneva, CH-1211 Geneva, Switzerland

  • Thierry Giamarchi

    • Université de Genève
    • University of Geneva, CH-1211 Geneva, Switzerland
    • DQMP, University of Geneva