*3.7.4 AC magnetic susceptibility (χ) of Zn0.94Fe0.03Ce0.03O nanoparticles*

The temperature-dependent real, χ<sup>0</sup> (T), and imaginary, χ00(T), components of the AC magnetic susceptibility of Ce-doped ZFO nanoparticles at frequencies 100, 300, 500, and 1000 Hz are shown in **Figure 9c** [40]. The frequency-independent peak maxima of χ<sup>0</sup> correspond to magnetic phase transition into an AF state with TN = 56 K is observed. A slight dispersion in the χ<sup>0</sup> (T) after the peak maxima is also observed. It indicates the existence of certain spin glass, ferromagnetic clusters and cluster glass magnetic type states [62]. However, the peak of χ00(T) increases with decreasing frequency. This is qualitatively different from the behavior of most spin glasses in which we expect an increase of the peak magnitude with increasing frequency. Thus, the obtained AC magnetization data supports the formation of the AF DMS materials with a certain cluster glass formation.

## **4. Conclusion**

The spintronic materials are the ferromagnetic oxide semiconductors for which both charge and spin degrees of freedom exist, but with weak ferromagnetism and small coercivity, there is a limitation in practical applications. Thus, these DMSs are widely characterized for the development of semiconductor devices, which create a new dimensionality to control and achieve high TC ferromagnetism. The first principle calculation revealed that the Cr, Fe, Co, and Ni dopants in ZnO prefer to occupy surface sites instead of bulk sites, while Mn exhibits no site preference and distributes uniformly in ZnO. In addition, the TM ions in ZnO are intrinsically AF because their substitution at Zn sites does not introduce any extra carriers. The interaction among localized spins on the TM ions and delocalized carrier electrons originating from the O vacancies is responsible for the required magnetic transition. The doping RE ions with intrinsic strong magnetic anisotropy and tailoring the coupling between dopants and defects should have a general approach toward a stable ferromagnetic order in DMS ZnO. The observed magnetism of DMS ZnO for both TM and RE ions might result with BMPs in oxygen vacancies.

### **Acknowledgements**

This research work is financially supported by CSIR India, for giving a Senior Research Associate fellowship (Pool Scientist; letter No. B-12287).

**Author details**

**127**

Kuldeep Chand Verma1,2

1 Department of Physics, Panjab University, Chandigarh, India

\*Address all correspondence to: dkuldeep.physics@gmail.com

provided the original work is properly cited.

2 CSIR-Central Scientific Instruments Organisation, Chandigarh, India

*Diluted Magnetic Semiconductor ZnO: Magnetic Ordering with Transition Metal…*

*DOI: http://dx.doi.org/10.5772/intechopen.90369*

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

*Diluted Magnetic Semiconductor ZnO: Magnetic Ordering with Transition Metal… DOI: http://dx.doi.org/10.5772/intechopen.90369*
