Direct determination of the Tomonaga-Luttinger parameter K in quasi-one-dimensional spin systems
Résumé
We test the analytical formula for the enhancement of the nuclear magnetic resonance rate 1/T1 by the critical spin fluctuations, over the simple power-law dependence predicted for a purely one-dimensional spin system, recently derived in the random phase approximation [M. Dupont et al., Phys. Rev. B 98, 094403 (2018)]. This prediction is experimentally confirmed by excellent fits to the published temperature dependence of 1/T1 data in the two representative spin compounds, (C7H10N)2CuBr4 (DIMPY) and BaCo2V2O8, providing at the same time a direct and convenient experimental determination of the Tomonaga-Luttinger-liquid parameter K, very well in agreement with theoretical predictions.