Observation of the Strong Negative Anomalous Hall Effect in Co Ion-implanted ZnO Single Crystals

Eighty-keV Co ions with a dose of 3 × 10 16 ions/cm2 were implanted into high-quality 0.5-mm-thick ZnO (0001) single crystals with very low carrier concentration of n = 2.0 × 1013/cm3. The implanted samples were post-annealed at 700, 800, and 900 ℃by rapid thermal annealing in a N2 atmosphere. The structural, magnetic, and transport properties of Co-ion-implanted ZnO were investigated. The Co K-edge extended X-ray absorption fine structure analysis revealed the coexistence of Co-Co and Co-Zn bonds. The Co ions substituted into Zn sites form Zn1−xCoxO. Magnetoresistance (MR) data showed a sign change from positive to negative between 50 K and 77K. A strong negative anomalous Hall effect (SNAHE) was observed in the temperature range with a positive MR. The sign change in the observed SNAHE seems to support the theory of Burkov and Balents. KCI Citation Count: 1