Nominally pure CuGeO₃

In Fig.55, $\mu$SR spectra of the nominally pure system are shown. There was slow relaxation observed below $T\sim 3$ K, but, as shown by the longitudinal field (LF) measurements in the inset, the relaxation is in the fast fluctuation regime; in the LF measurements, the relaxation was present up to LF$\sim 200$ G, while the zero-field relaxation rate corresponds to $\delta H\sim 6$ G, if it were caused by static field distribution. (See section 3.4 for $\mu$SR spectroscopic technique.) Our $\mu$SR measurements of the nominally pure CuGeO₃ confirmed the absence of static order down to 50 mK.

  

Figure 55: $\mu$SR spectra of the nominally pure CuGeO₃. The inset is longitudinal field decoupling measurements to investigate field fluctuations. The solid lines are fits with square-root exponential function, which is appropriate for paramagnetic dilute spin systems (see section 3.2 in Chapter 3).