Fig. 3: Temperature evolution of magnetic excitations.

a–c Temperature dependence of the magnetic Raman continuum in (bb), (cc), and (bc) polarizations. The green and pink shadings mark the characteristic energy scales of one-pair and two-pair spinon–antispinon excitations. d–f Color plots of the magnetic Raman intensity in the T-ω plane. The horizontal dashed lines indicate the onset of short-range ordering T_SO = 27 K and the intrachain interaction J. g Peak energy of the two-pair spinon–antispinon continuum as a function of temperature for (bb) and (cc) polarizations. The solid lines are linear guides to the eye. The vertical dashed lines mark T_SO and the interchain interaction J′. h, i Temperature dependence of the integrated magnetic Raman intensity over the one-pair spinon-antispinon energy of ω = 30–60 cm⁻¹ and the two-pair spinon-antispinon energy of ω = 70–100 cm⁻¹. The solid lines are fits to an exponential function.