Fig. 3: Spin Relaxation and coherence extension of an ensemble of spin defects in BNNTs.

Semi-log plot of spin coherence and relaxation decays measured using various pulse sequences, illustrated in the insets. Colored dots represent experimental data, while lines correspond to fits. a The solid orange data points and fit depict the fluorescence contrast decay for the T₁ spin-lattice relaxation measurement (sequence shown in the top-right inset). The solid red squares and line correspond to the coherence decay measured via spin-locking experiments, yielding T_1ρ (pulse sequence shown in the inset on the left). In the inset, the raw data corresponding to both experiments are shown before normalization. R₁ and R₂ represent the two readouts for measurement and normalization/noise subtraction, respectively (see “Methods” section for more details). b The cyan dashed curve and dots show coherence decay measured using a simple Hahn-echo sequence (one π-pulse), from which the \({T}_{2}\) constant is extracted. All other dashed curves and colored dots represent coherence decays measured using CPMG sequences with an increasing number of π-pulses, N (pulse sequence shown top-right inset). The bottom-left inset plots the coherence times \({{{{\rm{T}}}}}_{2,{{{\rm{CPMG}}}}}^{({{{\rm{N}}}})}\) as a function of N, fitted to a power law model.