Magnetocapacitance Effect in a Metal‐CdCr2Se4 Junction

The change in capacitance, due to an applied magnetic field, of a metal‐CdCr2Se4 junction, made by evaporating silver onto an In‐doped CdCr2Se4 single‐crystal surface, has been studied. It was found that the capacitance increased with increasing magnetic field and the rate of increase was found to increase with increasing temperature. On application of a magnetic field of 6 kOe, the capacitance C was increased by 1% at 77°K and by 20% at 98°K. Observation of the C vs bias voltage V characteristics in the presence and absence of the magnetic field showed that C−2 increased linearly with V and that the increase in capacitance is ascribed to the decrease in barrier height of the junction. A theoretical expression for the relative change of capacitance ΔC/C due to an applied magnetic field was derived taking into account the exchange interaction of electrons in the conduction band and donor levels with localized spins, which contributes to the magnetic properties of the material. Agreement between theory and ...