Two magnetic regimes in doped ZnO corresponding to a dilute magnetic semiconductor and a dilute magnetic insulator

Abstract

Films of ZnO doped with magnetic ions, Mn and Co and, in some cases, with Al have been fabricated with a very wide range of carrier densities. Ferromagnetic behaviour is observed in both insulating and metallic films, but not when the carrier density is intermediate. Insulating films exhibit variable range hopping at low temperatures and are ferromagnetic at room temperature due to the interaction of the localised spins with static localised states. The magnetism is quenched when carriers in the localised states become mobile. In the metallic (degenerate semiconductor) range, robust ferromagnetism reappears together with very strong magneto-optic signals and room temperature anomalous Hall data. This demonstrates the polarisation of the conduction bands and indicates that, when ZnO is doped into the metallic regime, it behaves as a genuine magnetic semiconductor.

The manuscript has been improved following suggestions from the referees and is now in press with Phys Rev Lett

References in corpus (3)

• Room temperature magneto-optics of ferromagnetic transition-metal doped ZnO thin films
• Carrier-induced ferromagnetism in n-type ZnMnAlO and ZnCoAlO thin films at room temperature
• Effect of the s,p-d exchange interaction on the excitons in (Zn,Co)O epilayers

Cited by in corpus (7)

• Room temperature ferromagnetism in carbon-implanted ZnO
• Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO
• Magnetic states at the Oxygen surfaces of ZnO and Co-doped ZnO
• Non-DMS related ferromagnetism in transition metal doped zinc oxide
• Nitrogen defects and ferromagnetism of Cr-doped AlN diluted magnetic semiconductor from first principles
• Ferromagnetic ordering in dilute magnetic dielectrics with and without free carriers
• Theory of magnetism with temporal disorder applied to magnetically doped ZnO