Aggregation-based growth and magnetic properties of inhomogeneous Cu-doped ZnO nanocrystals

Abstract

The authors report on the ferromagnetic ordering in 1.86at.% Cu-doped ZnO nanocrystals synthesized by a solvothermal route. The distribution of Cu in ZnO lattice was inhomogeneous. In the Cu-poor cores, a spin-split acceptor impurity band model was proposed to explain the ferromagnetism. While in the Cu-rich surface layers, the shallow donorlike defects generated by imperfect oriented attachment could not only compensate a few holes but also readily occupy the Cu 3d states to destroy CuO4 tetrahedra, hence resulting in the short-range antiferromagnetic clusters. As a result, an interesting exchange biasing phenomenon took place at the ferromagnetic/antiferromagnetic interface.

Optical and Magnetic Properties of Copper Doped Zinc Oxide Nanofilms

“…The saturation magnetizations are about 0.24 μB/Cu 2+ (0.51 emu/g) and 0.26 μB/ Cu 2+ (0.55 emu/g) at 5 K and 300 K, respectively. Thus saturation magnetization is higher than the results of previous report [30]. Besides, we note that the saturation magnetization, remanent magnetization, and coercivity at 300 K are very close to those of at 5 K. Therefore, it can be concluded that the Curie temperature of this samples are above 300 K.…”

Comparative Study of Room‐Temperature Ferromagnetism in Cu‐Doped ZnO Nanowires Enhanced by Structural Inhomogeneity

“…953.17 eV, respectively, similar to the result of Cu-doped ZnO nanocrystals. [14,25] Some satellite peaks are associated with these two peaks. A Gaussian fitting determines the ratio of Cu 2þ /Cu 1þ to be 80.4:19.6, in good agreement with the results of previous reports.…”

“…A Gaussian fitting determines the ratio of Cu 2þ /Cu 1þ to be 80.4:19.6, in good agreement with the results of previous reports. [14,25] Unlike Cu 2þ , Cu 1þ has fully filled 3d orbitals (3d 10 4s 0 ) and hence does not contribute to ferromagnetism.…”

Effects of Cu diffusion-doping on structural, optical, and magnetic properties of ZnO nanorod arrays grown by vapor phase transport method

“…40 Cu 2p3/2 and 2p1/2 core levels of the sample were fitted with Gaussian functions and centered at 933.7 and 953.5 eV, respectively, implying that Cu is in a divalent valence state, which is good agreement with the other studies in the literature. 41,42 Furthermore, a satellite peak is observed at binding energies in the range of 940-945 eV. CuO (Cu 2þ ) differs from metallic copper (Cu 0 ) and Cu 2 O (Cu 1þ ) because Cu 2þ is known to have Cu 2 p satellite peaks at higher binding energy associated with the existence of Cu 3 d hole states (Cu 3 d 9 ).…”