NONCOLLINEAR INTERLAYER COUPLING ACROSS A SEMICONDUCTOR SPACER

Based on the extended s-d exchange model. which includes both isotropi c and anisotropic spin interactions between conduction electrons and l ocal states, we have derived analytically the interlayer coupling acro ss a semiconductor spacer with a general band structure. Both Heisenbe rg-type and Dzyaloshinski-Moriya (DM) - type Ruderman-Kittel-Kasuya-Yo sida-like interlayer coupling are obtained as a result of spin-orbit i nteraction. The interlayer coupling decreases exponentially with space r thickness and the oscillation period depends on the band structure a nd orientation of spacers. Our result is different from previous theor y; in particular, the DM-type interlayer exchange coupling offers a na tural explanation to the noncollinear alignment of neighboring ferroma gnetic layers as were observed in recent experiments on magnetic-semic onductor multilayer structures.