Giant dielectric permittivity and magneto-capacitance effect in YBaCuFeO 5

Abstract We prepare polycrystalline YBaCuFeO 5 and identify the unusually high dielectric permittivity of ~ 10 4 on the order of magnitude, which has only weak temperature dependence between 90 K and 300 K. The nonlinear I - V characteristics are also observed. The impedance spectroscopy experiments reveal the crucial role played by grain boundary barriers in modulating the electrical properties. The giant-dielectric phenomenon could be attributed to the Maxwell–Wagner relaxation effect. It is surprising to observe large magneto-capacitance effect, which may be attributed to the inhomogeneity in samples.