Unexpected magnetic phase in the weakly ordered spin- 12 chain cuprate Sr2CuO3

Abstract

The magnetic phase diagram of a spin-1 2 chain antiferromagnet Sr 2 CuO 3 is studied by an ultrasound phasesensitive 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)] 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.

Two-band Conduction and Nesting Instabilities in Superconducting Ba$_2$CuO$_{3+δ}$: a First Principles Study

“…III J=1640 K, J ⊥ ∼ 10 K, this expression gives T N in the neighborhood of 25 K. His expression with a single interchain coupling does not fit closely with the Ba 2 CuO 3 structure with several (small) interchain couplings that we obtain, so we have used the largest. Within the uncertainty of the exchange couplings and the logarithmic dependence of the expression, this is similar to but somewhat larger than the case of Sr 2 CuO 3 [24], which means that Ba 2 CuO 3 is also near the regime of the 1D Luttinger-liquid quantum-critical phase.…”

“…at the δ = 0 phase, would have a pure 1D Cu-O P chain lattice, but that stoichiometry has not been well investigated yet. The chain lattice in the sister compound Sr 2 CuO 3 has been intensively investigated as an ideal 1D Heisenberg S = 1 2 antiferromagnetic (AFM) system for over 20 years [20][21][22][23][24].…”