Temperature-dependent paramagnetic susceptibilities ofCu2+andCo2+

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

“…[9] The dominant bivalent Cu ions observed in our XPS study, in conjunction with a trigonal crystal field, support the Jahn-Teller distortion. [39] The bifurcation of the M-H curves below 340 K in both samples resembles the results obtained in Cu-doped ZnO nanocrystals. [25] We note that the absence of blocking behavior in the ZFC curves excludes the existence of magnetic nanoclusters, [40] agreeing with the theoretical prediction.…”

A study on the Raman spectra of Al-doped and Ga-doped ZnO ceramics

“…Moreover, Onodera [14] and Joseph et al [15] have found a ferroelectric property in Li-doped ZnO. Recently, also, it has been reported that transition-metal-doped ZnO shows magnetic properties [16][17][18]. Therefore, because ZnO has such a variety of physical properties according to impurity doping, it is necessary to study the impurity-doping mechanism in ZnO extensively.…”

Magnetic circular dichroism of ferromagnetic Co2+-doped ZnO

“…netic, with strongly temperature-dependent MCD intensities growing in at low temperatures consistent with previous measurements. 3,4,8,9 Upon exposure of the paramagnetic Co 2+ : ZnO films to Zn vapor, the 300 K MCD intensity was strongly enhanced and its band shape changed ͓Fig. 1͑c͒, solid line͔.…”

“…In other cases, evidence points toward intrinsic ferromagnetism that relies on the presence of n-or p-type lattice defects. Co 2+ : ZnO grown without deliberate incorporation of such defects has been studied extensively and exhibits only paramagnetism ͑with weak local antiferromagnetic super-exchange͒, 3,4 but weak ferromagnetism can be induced by vacuum annealing 4 and stronger ferromagnetism can be achieved by growth under lower O 2 partial pressures, 5 both linked to introduction of shallow donor defects. Quantitatively reversible 300 K ferromagnetic ordering in Co 2+ : ZnO was demonstrated 6 by Zn vapor diffusion ͑"on"͒ and subsequent aerobic reoxidation ͑"off"͒, attributed to introduction and removal of the native shallow donor, interstitial zinc ͑Zn i ͒.…”