  The ABO3 type charge-ordered antiferromagnetic Nd0.50Ca0.50MnO3 (NCMO)
manganite is doped at A-site by 3 % of Ba2+ for Ca2+. The resulting system,
Nd0.50Ca0.47Ba0.03MnO3 (NCBMO), is studied for the effects of Ba doping on the
magnetic and electronic properties. On application of magnetic field to NCBMO,
strongly correlated successive sharp metamagnetic and electronic transitions
are observed from antiferromagnetic-insulating to ferromagnetic-metallic state
at 2.5 K. The critical magnetic field (Hc) required for metamagnetism is found
to reduce drastically from 15 T for undoped NCMO to 3 T for NCBMO. On
increasing the temperature, the Hc of NCBMO passes through a minimum. This
behavior of Hc of NCBMO contrasts to that of NCMO. The results are discussed in
context of A-site cation disorder and size.
