  By performing a series of thermodynamic measurements in an applied magnetic
field $H_{\textrm{ext}}$, we investigated the effects of Eu substitution on the
Pr sites in filled skutterudite compound Pr$_{1-x}$Eu$_x$Pt$_4$Ge$_{12}$ ($ 0
\leq x \leq 1$). A heat capacity Schottky anomaly is present over the whole
doping range. For the samples with $x > 0.5$, these Schottky anomaly peaks
shift to lower temperature with increasing $H_{\textrm{ext}}$. We argue that
this behavior reflects the antiferromagnetic (AFM) ordering of the Eu moments,
as the AFM transition is suppressed by $H_{\textrm{ext}}$. The Schottky peaks
in the samples with $x \leq 0.5$ shift to higher temperatures with increasing
magnetic field, signaling the presence of an internal magnetic field due to
short-range AFM correlations induced by magnetic moments of neighboring Eu
sites. In low $H_{\textrm{ext}}$, the Schottky gaps show a non-linear
relationship with $H_{\textrm{ext}}$ as the magnetic moments become weakly
magnetized. In high $H_{\textrm{ext}}$, the magnetic moments of Eu sites become
completely aligned with $H_{\textrm{ext}}$. Thus, increasing $H_{\textrm{ext}}$
does not further increase the magnetization, hence the Schottky gaps increase
linearly with $H_{\textrm{ext}}$
