acta physica slovaca

Acta Physica Slovaca 57, No.4&5, 565-907 (2007) (342 pages)

Semiconductor Spintronics

Jaroslav Fabiana, Alex Matos-Abiaguea, Christian Ertlera, Peter Stanoa, Igor Zuticb

  aInstitute for Theoretical Physics, University of Regensburg
   93040 Regensburg, Germany
  bDepartment of Physics, State University of New York at Buffalo,
   Buffalo NY, 14260, USA

Full text: ::pdf :: (received 29 June 2007, accepted 04 July 2007)

Abstract: Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. While metal spintronics has already found its niche in the computer industry - giant magnetoresistance systems are used as hard disk read heads - semiconductor spintronics is yet to demonstrate its full potential. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge coupling, and spindependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent interaction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In view of the importance of ferromagnetic semiconductor materials, a brief discussion of diluted magnetic semiconductors is included. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief reviews of relevant recent achievements in the field.

PACS: 72.25.-b, 72.25.Rb, 75.50.Pp, 85.75.-d
Keywords: Spintronics, Magnetic semiconductors, Spin injection, Spin relaxation, Spin transistor, Spin-orbit coupling

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