Unexpected magnetic phase in the weakly ordered spin-1/2 chain cuprate Sr2CuO3

E. G. Sergeicheva, S. S. Sosin*, D. Gorbunov, S. Zherlitsyn, G. D. Gu, I. A. Zaliznyak

*Corresponding author for this work

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Abstract

The magnetic phase diagram of a spin-1/2 chain antiferromagnet Sr(2)CuO(3 )is studied by an ultrasound phase-sensitive detection technique. The system is in the extreme proximity of the Luttinger-liquid quantum-critical point and we observe an unusually strong effect of magnetic field, which is very weak compared to the in-chain interaction, on the Neel ordering temperature. Inside the ordered phase, we detect an unexpected, field-induced continuous phase transition. The transition is accompanied by softening of magnetic excitation observed by electron-spin resonance, which in previous work [E. G. Sergeicheva et al., Phys. Rev. B 95, 020411(R) (2017)] was associated with a longitudinal (amplitude) mode of the order parameter. These results suggest a transition from a transverse collinear antiferromagnet to an amplitude-modulated spin-density-wave phase in a very weak magnetic field, which is unexpected for a system of weakly coupled Heisenberg spin-1/2 chains.

Original languageEnglish
Article number201107
Number of pages5
JournalPhysical Review B
Volume101
Issue number20
DOIs
Publication statusPublished - 15 May 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • QUANTUM CRITICALITY
  • NEEL TEMPERATURE
  • FIELD
  • ANTIFERROMAGNETS
  • SUSCEPTIBILITY
  • DYNAMICS
  • S=1/2

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