Pressure sensitivity (up to 1 GPa) of the electrical resistivity and of the ac susceptibility was measured for low electron doping levels of Ca$_{ 1-x}$Y$_x$MnO$_3$ (CYMO) and of Ca$_{ 1-x}$Sm$_x$MnO$_3$ (CSMO) ceramic samples (0.05 $\leq$ x $\leq$ 0.15). A very weak pressure dependence of the Curie temperature (T$_c$) was observed for both systems ($\sim$ 6 K GPa$^{ -1}$), when compared to the hole-doped manganites of the same T$_c$ ($\sim$ 20 K GPa$^{ -1}$). Our results can be interpreted within a modified Double Exchange scenario, where pressure alters the reduction of the bandwidth produced by the electron-phonon interaction associated with small Fr\"{ o}hlich polarons in the weak to intermediate coupling regime.
Categories: cond-mat.str-el