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.

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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