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Nitrides for Spintronics - Magnetic Moments and Spin Lifetimes in Nitrides

Jacek A. Majewski 

Technische Univ. München, Walter Schottky Institut, Am Coulombwall 3, Garching D-85748, Germany


Theoretical predictions and later experimental findings of room-temperature ferromagnetism in Mn doped GaN have awoke considerable interest in nitrides as promising materials for spintronics. The ferromagnetic GaN:Mn could be a potential candidate for spin-polarization field emitter and might be useful in the development of all semiconductor spintronic devices. However, the physical mechanisms of possible room-temparature ferromagnetism in GaN:Mn are not well understood yet. Here, we provide critical review of existing theories and experimental data for GaN:Mn and discuss prospects of ferromagnetism in GaN doped with other transition metals.
Further, we discuss the problem of the spin decoherence in nitride heterostructures. In standard semiconductors, the electric field dependence of the spin splitting of energy bands (Rashba effect) has a marked influence on the spin dynamics and spin relaxation processes. This issue becomes much more relevant in nitride heterostructures. In view of their huge (of order few MV/cm) electric fields that originate in their strong piezo- and pyroelectric character, one may anticipate very significant spin splitting. In nitride heterostructures grown along the c-axis and in the neighborhood of the Γ point, the spin splitting of each energy band is dominated by the k-linear isotropic term. In AlN/GaN/AlN quantum wells, we find the spin splitting for the lowest conduction band to initially increase with increasing quantum well width but to saturate at well widths of 4 nm. We find that this limiting value is an order of magnitude smaller than in GaAs based heterostructures and agrees fairly well with recent experiments. These results indicate GaN heterostructures to be promising candidates for spintronic applications that require long electronic spin lifetimes.


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Presentation: invited oral at E-MRS Fall Meeting 2004, Symposium C, by Jacek A. Majewski
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-04-30 20:33
Revised:   2013-03-03 18:54