Lack of ferromagnetism in n-type cobalt-doped ZnO epitaxial thin films.
Epitaxial thin films of cobalt-doped ZnO (Co:ZnO) were deposited by pulsed laser deposition (PLD) on both c-plane and r-plane sapphire (Al{sub 2}O{sub 3}). The films exhibited high structural quality with narrow x-ray diffraction (XRD) rocking curve peak widths. X-ray absorption spectroscopy (XANES and EXAFS) confirmed well-ordered Co substitution for Zn in ZnO without the formation of secondary phases. A wide range of n-type conductivities (10{sup -4}-10{sup 5} {Omega} cm) was achieved by controlling the deposition conditions, post-annealing in vacuum, and/or addition of Al during deposition. Despite the high structural quality of the Co:ZnO thin films, no significant room temperature ferromagnetism was observed under any processing or treatment conditions. The lack of ferromagnetism indicates that itinerant conduction band electrons alone are not sufficient to induce ferromagnetism in Co:ZnO, even when the carrier concentration is a significant fraction of the magnetic dopant concentration. The implications of this observation are discussed.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC; NSF; Sloan Foundation; Dretfus Foundation; Research Corp.
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 934655
- Report Number(s):
- ANL/XSD/JA-61011
- Journal Information:
- NJP, Journal Name: NJP Journal Issue: May 23, 2008 Vol. 10
- Country of Publication:
- United States
- Language:
- ENGLISH
Similar Records
Atomic Oxygen Sensors Based on Nanograin ZnO Films Prepared by Pulse Laser Deposition
Magnetism of Co doped ZnO with Al codoping: Carrier-induced mechanisms versus extrinsic origins