Anomalous dielectric constant of half-doped manganite La0.5Ca0.5MnO3

•ɛ′(T) of La0.5Ca0.5MnO3 are investigated by EOM GF.•The intensity of ɛ′(T) reduced with the increase of |ɛJT|, V, U.•TP rises as |ɛJT|, V, and U increase.•TP remains unchanged and ɛ′(T) increased with the increase of g.•The calculated results of ɛ′(T) are explained theoretically.

The anomalous dielectric constants ɛ′(T) of half-doped manganite La0.5Ca0.5MnO3 are investigated by using equation of motion of Green’s function technique. The half-doped manganite is described by the Kondo-lattice model in the double exchange limit taking account of the Jahn–Teller distortions and the super-exchange interaction between the localized electrons. It is found that the intensity of ɛ′(T) reduces with the increase of |ɛJT|, V, U, respectively. It is also observed that the transition temperature TP rises as |ɛJT|, V, and U increase, respectively. It is worth noting that TP remains unchanged and ɛ′(T) strength increases with the increase of g. The calculated results of dielectric constants are also explained theoretically. Those behaviors are in qualitative agreement with experimental results.