Magnetic Semiconductors


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Recent Milestones
  • Ferromagnetic transition temperature in excess of 100 K in (Ga,Mn)As diluted magnetic semiconductors (DMS's).
  • Spin injection from ferromagnetic to non-magnetic semiconductors and long spin-coherence times in semiconductors.
  • External electric field control of ferromagnetism in DMS quantum wells.
  • Ferromagnetism in Mn digital (delta) doped III-V semiconductors.
  • Ferromagnetism in Mn doped group IV semiconductors.
  • Room temperature ferromagnetism in (Ga,Mn)N, (Ga,Mn)P, and digital-doped (Ga,Mn)Sb.
  • Large magnetoresistance in ferromagnetic semiconductor tunnel junctions.
Origins of Ferromagnetism in (III,Mn)V Semiconductors
  • Mn acts as an acceptor when substituting for a cation (group III element).
  • Mn2+ ion has angular momentum L=0 and spin S=5/2.
  • Ferromagnetism in metallic DMS's occurs because of interactions between Mn local moments that are mediated by holes in the semiconductor valence band.
Novel and Attractive Physical Properties
  • Spintronics in semiconductors
  • Interplay between itinerant and local magnetic moments.
  • Itinerant spin polarization & strong spin-orbit coupling --> magnetic properties controlled by external (e.g. electric) fields; transport and optical properties sensitive to the magnetic state.


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