Figure 1

Dependence of the normalized ${}^{137}\mathrm{Ba}$ spin-echo intensity on the pulse separation time $\tau$ at 300 K; $B_{\mathrm{ext}}$ parallel to the $c$ axis of ${\mathrm{YBa}}_2{\mathrm{Cu}}_4{\mathrm{O}}_8$. Results for zero field and for $B_{\mathrm{ext}}=0.23\mathrm{mT}$. Solid lines were fitted to data with Eq. (1), see text. The inset shows ${}^{137}\mathrm{Ba}$ resonance line at 30.9 MHz, no external field, 300 K.Reuse & Permissions

Figure 2

Spin-echo intensity decay with pulse separation time $\tau$ for zero-field at 300 K and 90 K. No distinguishable change in the normalised intensity was detected in the pseudogap phase.Reuse & Permissions

Figure 3

Normalized spin-echo intensity decay with the pulse separation time $\tau$ for some applied external fields $B_{\mathrm{ext}}$, at $T=90\mathrm{K}$, for ${}^{137}\mathrm{Ba}$ in ${\mathrm{YBa}}_2{\mathrm{Cu}}_4{\mathrm{O}}_8$. The corresponding fields $B_{\mathrm{loc}}$ were calculated by fitting Eq. (1) to the data, see text. Experimental data are represented by open circles; fitted results by solid lines. Panel (a) shows data and results for magnetic fields $B_{\mathrm{ext}}=0$, 0.08, 0.12, 0.16, 0.23, and 0.38 mT applied parallel to the crystalline $c$ axis; panel (b) for $B_{\mathrm{ext}}=0$, 0.08, 0.12, and 0.23 mT applied perpendicular to the $c$ axis. Data sets were shifted vertically for clarity. Fields are given next to each curve.Reuse & Permissions