In order to estimate the characteristic field distribution width
(), we phenomenologically analyzed the spectra with
a stretched exponential function, . Since the
stretching power represents the shape of the field
distribution, we assumed that it is temperature independent; we
obtained from the lowest temperature data and fixed it all
through the fit ( and 2.00 for the *x*=2, 4 and
8 % sample, respectively.) Near the Néel temperature, the
relaxation amplitude ( ordered volume fraction) decreased as
the temperature go through the transition temperature; this result suggests
a distribution of . We introduced a paramagnetic volume
fraction (), and analyzed the spectra with the
functional form of:

In Fig.57, we show the field width
() and the paramagnetic volume fraction () as a
function of temperature.
The field width () saturates at low temperatures, being
consistent with the static order. In the inset of
Fig.57a, the saturation magnitude of the field
width [] are plotted as a function of the
Zn concentration (*x*). It was found that mimics the Zn concentration (*x*) dependence of (Fig.53).

The temperature dependence of the paramagnetic fraction ()suggests a distribution of Néel temperatures; with an assumption
of Gaussian distribution to (), the
average Néel temperature and the spread have been deduced as shown in Fig.57b.

In Fig.58, results of longitudinal field (LF)
decoupling measurements are shown. The spectra exhibited the
characteristics of static relaxation, namely, time independent muon
spin polarization at and the decoupling field
comparable to the field distribution width (). The
solid lines in Fig.58 are static Gaussian
Kubo-Toyabe function (eq.19), using the field-width
parameter () obtained from the stretched exponential fit shown
in Fig.56b. In small LF's, the Gaussian
Kubo-Toyabe function described the recovery at long times relatively
well; the deviation at higher LF's may suggest that there exists a larger
local field component than true Gaussian distribution assumes.