Recent progress on magnetic-field studies on quantum-spin-liquid candidates

Ma Zhen¹, Ran Kejing¹, Wang Jinghui¹, Bao Song¹, Cai Zhengwei¹, Li Shichao¹, Wen Jinsheng^{1, 2, †}

(color online) (a) Spin excitation gap Δ of Herbertsmithite obtained by fitting NMR spectra with a temperature range up to 4.2 K (circles) and 10 K (crosses). Dashed and dotted lines represent the best fits under the constraint of S = 1 and 1/2, respectively. The solid line represents the best free-parameter fit. From Ref. [80]. (b) Transition temperature T_c versus magnetic field phase diagram of Herbertsmithite. The inset plots Δ as a function of T_c. From Ref. [81].