Low-frequency negative capacitance in La0.8Sr0.2MnO3/Nb-doped SrTiO3 heterojunction

Low-frequency (100Hz⩽f⩽1MHz) dielectric properties of La0.8Sr0.2MnO3∕Nb-doped SrTiO3 heterojunctions were investigated in detail at room temperature. Negative capacitance was observed at low frequencies under positive dc biases. This phenomenon was found to result from the combinational contributions from the Maxwell–Wagner interfacial relaxation and the dipolar relaxation related to detrapped carriers which give rise to inductive effect under an applied electric field.