Magnetocapacitance: Probe of Spin-Dependent Potentials

The magnetic field dependence of the capacitance of $\mathrm{P}\mathrm{d}\mathrm{\text{−}}{\mathrm{A}\mathrm{l}\mathrm{O}}_x\mathrm{\text{−}}\mathrm{A}\mathrm{l}$ thin-film structures has been measured. The observed quadratic dependence of capacitance on the magnetic field is consistent with a theoretical model that includes the effect of a spin-dependent electrochemical potential on electron screening in the paramagnetic Pd. This spin-dependent electrochemical potential is related to the Zeeman splitting of the narrow $d$ bands in Pd. The quantitative details depend on the electronic band structure at the surface of Pd.