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

Spintronics or spin transport electronics is an emerging technology exploiting both intrinsic spin of the electron and associatedmagnetic moment, in addition to its fundamental electronic charge. Here we present a novel approach in fabricating and characterizingspintronics materials. A wide band gap material such as Zinc Oxide (ZnO) is one of the strong candidates for spintronics materials. Byimplanting transition metal (3d) and rare earth materials (4f) into ZnO host, room temperature ferromagnetism (RTFM) can be obtained inall implanted samples.Resonant Raman Scattering was observed in Co doped ZnO films due to presence of defect related levels. This defect related levelsform bound magnetic polaron which trigger RTFM in the Co doped films. The magnetization of Eu implanted ZnO showed a free electroncarrier 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 of1200 Oe at ambient temperature. This was found and verified through complementary magnetic measurement comprising magneticmeasurements 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. Theanomalous 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. Thelocalized 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 ~ 1020cm-3. The AHE curves are quantitatively consistence with M-H loops, indicating the existence of spin-polarized carriers. The observationof room temperature AHE in ZNO based diluted magnetic spintronics is useful for understanding the origin of ferromagnetism andprovide significant potential for use in the room temperature spintronics devices