Abstract
The magnetic phase diagram of a spin-12 chain antiferromagnet Sr2CuO3 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 Néel 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)2469-995010.1103/PhysRevB.95.020411] 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-12 chains.
Original language | English |
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Article number | 201107 |
Number of pages | 5 |
Journal | Physical Review B |
Volume | 101 |
Issue number | 20 |
DOIs | |
Publication status | Published - 15 May 2020 |
MoE publication type | A1 Journal article-refereed |
Keywords
- QUANTUM CRITICALITY
- NEEL TEMPERATURE
- FIELD
- ANTIFERROMAGNETS
- SUSCEPTIBILITY
- DYNAMICS
- S=1/2