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Session Q14 - DCMP: SEMICONDUCTORS: MAGNETISM
Mixed session, Friday morning, March 24, 8:00
Room J4, San Jose Convention Center
We report neutron diffraction studies of CdTe/MnTe and ZnTe/MnTe superlattices with very thin non-magnetic spacers. The results show clear evidence of the formation of long-range AF spin ordering within the MnTe layers and of magnetic coupling between the MnTe layers across the CdTe and ZnTe spacers (even though the carrier concentration in these semiconducting materials is too low to give rise to significant RKKY exchange). While in the CdTe/MnTe systems the interlayer correlations appear to be remarkably stable up to the Néel point, the spectra from ZnTe/MnTe clearly show a transition from low- T ``in-phase'' interlayer coupling to a high- T ``antiphase'' correlation sequence. Such behavior indicates a change of the interaction sign with T . The processes involved may be similar to those of Bruno's model B 49, 13231 (1994) for coupling between FM films across an insulating barrier (in which strong T -dependence is a characteristic feature).