AVS 52nd International Symposium
    Thin Films Thursday Sessions
       Session TF+EM-ThA

Invited Paper TF+EM-ThA7
Ferromagnetic Behavior in Indium Oxide Based Transparent Semiconductors

Thursday, November 3, 2005, 4:00 pm, Room 306

Session: Transparent Conducting Oxides
Presenter: J. Moodera, Massachusetts Institute of Technology
Correspondent: Click to Email

Ferromagnetic semiconductors are expected to provide smooth transition for spin injection and transport needed for spin based technology leading to multifunctional devices of the future. Although the field of dilute magnetic semiconductors has been explored for a long time, in recent years there is increased activity due to the significant increase in the ferromagnetic ordering temperature (T@sub c@) of Ga@sub 1-x@Mn@sub x@As system and in various doped oxide systems, despite the existing skepticism in the latter area. We have observed ferromagnetism well above room temperature in Mn doped indium-tin oxide (ITO), Cr doped indium oxide (IO) as well as Mn doped zinc oxide films by reactive evaporation as well as sputtering. Films grown on sapphire (0001) and on silicon show excellent magnetic behavior with a moment ranging from 1 to 5µ@sub B@ for low concentrations of the dopant. Mn doped ITO and Cr doped IO are highly transparent as well as conducting. The electrical conduction is n-type with a carrier concentration in the range of 10@super 18@ to 10@super 20@ cm@super -3@. The charge carriers are seen to be spin polarized shown by the presence of anomalous Hall effect, revealing the magnetic interaction between itinerant electrons and localized Mn or Cr spins. What is interesting in these compounds is that the charge carriers can be independently varied independent of the dopant by the oxygen or the tin concentration in this transparent semiconductor for its easy integration into magneto-optoelectronic devices. In this talk the status of the field will be reviewed and compared with our work. Work carried out in collaboration with John Philip and Nikoleta Theodoropoulou. Supported by the CMI funds at MIT and NSF funds.