A new class of materials for use as a dielectric to separate various metallic layers within a magnetoresistive transducer. The materials include oxides of Ta, Hf, Zr, Y, Ti, or Nb. Thin films of these materials, when fabricated in accordance with the teachings of the invention, constitute dielectric films which maintain their integrity as insulators at thicknesses down to 5 nm. Additionally, the adhesion of this class of dielectrics equals or exceeds that of commonly used dielectrics.