Effect of magnetic field on the capacitance of the La_0.5Ca_0.5MnO₃‐based heterojunction

Abstract

Effects of interface decoration and ac frequency, under which the impedance is measured, on the magnetoelectric property have been experimentally studied for the heterojunctions of La0.5Ca0.5MnO3/SrTiO3:Nb and La0.5Ca0.5MnO3/LaMnO3(3nm)/SrTiO3:Nb. It is found that the impedance of the junction can be well described by an effective circuit of two R–C sub‐circuits in series well above 100 K. Magnetocapacitance emerges and develops as temperature decreases, and shows a strong frequency‐dependent character. The maximal magnetocapacitance, under a field of 5 T, is ∼30 and ∼35% with and without the buffer layer, respectively. The incorporation of the LaMnO3 layer shifts the upper temperature limit for significant magnetocapacitance from ∼120 to ∼200 K. Shrinkage of the depletion layer of the junction under magnetic field may be a main reason for the magnetoelectric effect observed here.