SELECTION-RULES FOR OSCILLATIONS OF THE GIANT MAGNETORESISTANCE WITH NONMAGNETIC SPACER LAYER THICKNESS

Oscillations of the giant magnetoresistance (GMR) with nonmagnetic spacer layer thickness are predicted in the current-perpendicular-to -plane (CPP) geometry. The methods of the quantum-well theory of the oscillatory exchange coupling are applied to the Kubo formula to derive general selection rules for the GMR oscillation periods. The selection rules are illustrated for single-orbital tight-binding and parabolic band models. They predict that the CPP GMR oscillates not only with the expected Fermi-surface period but also with additional periods determined by the potential steps between the magnetic and nonmagnetic layers.