The development of transition metal and rare earth codoping ZnO for spintronics application

Download files
Access & Terms of Use
open access
Copyright: Lee, Jiunn Jieh
Altmetric
Abstract
Spintronics or spin transport electronics is an emerging technology exploiting both intrinsic spin of the electron and associated magnetic moment, in addition to its fundamental electronic charge. Here we present a novel approach in fabricating and characterizing spintronics materials. A wide band gap material such as Zinc Oxide (ZnO) is one of the strong candidates for spintronics materials. By implanting transition metal (3d) and rare earth materials (4f) into ZnO host, room temperature ferromagnetism (RTFM) can be obtained in all implanted samples. Resonant Raman Scattering was observed in Co doped ZnO films due to presence of defect related levels. This defect related levels form bound magnetic polaron which trigger RTFM in the Co doped films. The magnetization of Eu implanted ZnO showed a free electron carrier concentration dependence, which increases dramatically when the free electron carrier exceeds ~1019cm-3. Compared with the mono-doped ZnO thin films, Co and Eu co-doped samples exhibit a stronger magnetization with a giant coercivity of 1200 Oe at ambient temperature. This was found and verified through complementary magnetic measurement comprising magnetic measurements using superconducting quantum interference device (SQUID) and the x-ray magnetic circular dichroism analysis (XMCD). The giant coercivity emerged from 3d/4f co-doped can be tailored shows a promising future for application requiring nonvolatility. The anomalous Hall Effect is observed in 3d/4f co-doped ZnO films due to interaction of spin and carrier of the 3d/4f co-doped ZnO. The localized 4f electrons of Eu ions interact strongly with host and 3d electron, give rise to negative magnetoresistance at low temperature. Room temperature anomalous Hall Effect (AHE) signal for the Co-Eu co-doped samples have free electron carrier in the range of ~ 1020 cm-3. The AHE curves are quantitatively consistence with M-H loops, indicating the existence of spin-polarized carriers. The observation of room temperature AHE in ZNO based diluted magnetic spintronics is useful for understanding the origin of ferromagnetism and provide significant potential for use in the room temperature spintronics devices.
Persistent link to this record
Link to Publisher Version
Link to Open Access Version
Additional Link
Author(s)
Lee, Jiunn Jieh
Supervisor(s)
Li, Sean
Creator(s)
Editor(s)
Translator(s)
Curator(s)
Designer(s)
Arranger(s)
Composer(s)
Recordist(s)
Conference Proceedings Editor(s)
Other Contributor(s)
Corporate/Industry Contributor(s)
Publication Year
2014
Resource Type
Thesis
Degree Type
PhD Doctorate
UNSW Faculty
Files
download public version.pdf 3.41 MB Adobe Portable Document Format
Related dataset(s)