Magnetic and transport properties of V-doped La$_{0.7}$Ca$_{0.3}$MnO$_{3}$

The effects of substitution of V for Mn on the electronic and the magnetic properties of La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ have been investigated. The samples show a reentrant magnetic behavior as the V doping is increased. The V doping into the Mn sites leads to a mixed-phase ground state consisting of the ferromagnetic insulating and the ferromagnetic metallic phases at low temperatures. The magnetic relaxation was observed in both the ferromagnetic and the reentrant spin-glass phases, which means the existence of frustration and magnetic disorder in the samples. It was found that the V-doped manganites with aging effect bear the characteristics of a reentrant ferromagnet.