XVIth International Workshop on
Quantum Systems in
Chemistry and Physics
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Towards Semiconductor GMR Devices: Tuning Interlayer Exchange Coupling of Magnetic Semiconductor Multilayers
Z. Tang, F. Sun, B. Han, Z. Q. Zhu and J. H. Chu
Key Laboratory of Polar Materials and Devices, Ministry of Education,East China Normal University, Shanghai 200241, P. R. China
Interlayer exchange coupling (IEC) plays an important role in manipulating transport properties of magnetic multilayers. It has demonstrated its technological impact in the form of metallic giant magnetoresistance (GMR) effect and has initiated the emergence of spintronics. Similarly, to fabricate semiconductor giant magnetoresistance devices, it is also essential to reversibly switch the interlayer exchange coupling of magnetic semiconductor multilayers between ferromagnetic and antiferromagnetic. However, after intensive studies since the late 80's, ones have realized that tuning the IEC in semiconductor multilayers is much more difficult than in metallic multilayers because either the antiferromagnetic IEC or the oscillatory IEC predicted by the conventional RKKY theory is usually absent in experiments.
In this work, first-principles calculations and an extended RKKY theory are employed to study the IEC in series model multilayers of diluted magnetic semiconductors. It is argued that the ferromagnetic IEC is an intrinsic characteristic of the magnetic semiconductor multilayers and to get the antiferromagnetic IEC, heavily doped spacer layers are essential. Based on the extended RKKY theory, we propose a prototype semiconductor giant magnetoresistance device consisting of Co-doped TiO2/VO2 diluted magnetic semiconductor multilayers, in which the reversibly tunable IEC is achievable via metal-insulator transition around 340 K.


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