  We study and compare magnetic and electron paramagnetic resonance behaviors
of bulk and nanoparticles of Nd(1-x)CaxMnO3 in hole doped (x = 0.4;NCMOH) and
electron doped (x = 0.6;NCMOE) samples. NCMOH in bulk form shows a complex
temperature dependence of magnetization M(T), with a charge ordering (CO)
transition at around 250 K, an antiferromagnetic (AFM) transition at around 150
K and a transition to a canted AFM phase/mixed phase at around 80 K. Bulk NCMOE
behaves quite differently with just a charge ordering transition at around 280
K, thus providing a striking example of the so called electron-hole asymmetry.
While our magnetization data on bulk samples are consistent with the earlier
reports, the new results on the nanoparticles bring out drastic effects of size
reduction. They show that M(T) behaviors of the two nano samples are
essentially similar in addition to the absence of the charge order in them thus
providing strong evidence for vanishing of the electron-hole asymmetry in
nanomanganites. This conclusion is further corroborated by electron
paramagnetic resonance studies which show that the large difference in the
g-values and their temperature dependence found for the two bulk samples
disappears as they approach a common behavior in the corresponding nano
samples.
