Magnetic moment of Mn2+ ions that are responsible for the ferromagnetic properties of ZnO:Mn nanocrystals

O.V. Kovalenko; V.Yu. Vorovsky

doi:10.15330/pcss.24.4.650-655

Authors

O.V. Kovalenko Oles Honchar Dnipro National University, Dnipro, Ukraine
V.Yu. Vorovsky Oles Honchar Dnipro National University, Dnipro, Ukraine

DOI:

https://doi.org/10.15330/pcss.24.4.650-655

Keywords:

magnetic moment, nanocrystals, ultrasonic aerosol pyrolysis, heat treatment, hydrogen

Abstract

The calculation of the magnetic moment of Mn²⁺ ions in ZnO:Mn (2 at%.) nanocrystals obtained by ultrasonic pyrolysis of aerosol which are responsible for their ferromagnetic properties is given. In order to investigate the influence of structural defects on the value of magnetic moment the samples were heat treated in air. The calculation was performed on the basis of the analysis of magnetization curves and EPR spectra. It was shown that the defective state of ZnO:Mn nanocrystals has a significant effect on the magnetic moment. The values of magnetic moment for the synthesized sample significantly exceed the values of magnetic moment compared to similar nanocrystals obtained by other methods. The assumption is made that this result is due to the presence of an additional component in the magnetization of the defective samples. In addition to the paramagnetism of Mn²⁺ ions, there may be the paramagnetism of the defective shell of ZnO:Mn nanocrystals. After the elimination of structural defects by heat treatment of samples in air and in a gas mixture with hydrogen, the magnetic moment for Mn²⁺ ions, which form the ferromagnetic properties of nanocrystals, was determined. The value of this magnetic moment is 0.02µB, where µB is the Bohr mangiton. Such ions, according to the model of bound magnetic polarons, are part of ferromagnetic clusters and take part in the formation of the ferromagnetic properties of the samples.

Keywords: magnetic moment, nanocrystals, ultrasonic aerosol pyrolysis, heat treatment, hydrogen.

References

T. Dietl, H. Ohno, Dilute ferromagnetic semiconductors: Physics and spintronic structures, Rev. Mod. Phys., 86, 187 (2014); https://doi.org/10.1103/RevModPhys.86.187.

K. Sebayang, D. Aryanto, S. Simbolon et al., Effect of sintering temperature on the microstructure, electrical and magnetic properties of Zn0.98 Mn0.02O material, IOP Conf. Series: Materials Science and Engineering, 309, 012119 (2018); https://doi.org/10.1088/1757-899X/309/1/012119.

M. Mustaqima, C. Liu, ZnO-based nanostructures for diluted magnetic semiconductor, Turkish Journal of Physics, 38 (3), 429 (2014); https://doi.org/10.3906/fiz-1405-17.

J.M.D. Coey, M. Venkatesan, C.B. Fitzgerald, Donor impurity band exchange in dilute ferromagnetic oxides, J. Nature Mater., 4 173 (2005); https://doi.org/10.1038/nmat1310.

A.M. Abdel Hakeem, Room-temperature ferromagnetism in Zn1−xMnxO, J. Magn. Magn. Mater., 322 (6), 709 (2010); https://doi.org/10.1016/j.jmmm.2009.10.046.

M. El-Hilo, A.A. Dakhel, Structural and magnetic properties of Mn-doped ZnO powders, J. Magn. Magn. Mater., 323, 2202 (2011); https://doi.org/10.1016/j.jmmm.2011.03.031.

O. V. Kovalenko, M. F. Bulaniy, V. Y. Vorovskiy, O.V. Khmelenkо, Photoluminescence and EPR spectrum of ZnO:Mn nanocrystals, Journal of Physics and Electronics 26 (1), 69 ( 2018); https://doi.org/10.15421/331811.

O.V. Kovalenko, V.Yu. Vorovsky, O.V. Khmelenkо, The effect of heat treatment on the magnetic properties of ZnO:Mn nanocrystals obtained by ultrasonic aerosol pyrolysis, Functional Materials 27(4), 687 (2020); https://doi.org/10.15407/fm27.04.687.

A. Abdel-Galil, M.R. Balboul, A. Sharaf, Synthesis and characterization of Mn-doped ZnO diluted magnetic semiconductors, Phys B, 477, 20 (2015); http://dx.doi.org/10.1016/j.physb.2015.08.001.

O.V. Brodovyj, et al., Magnetic Deformation Effect, Usp. Fiz. Met., 2, 131 (2001); https://doi.org/10.15407/ufm.02.02.131.

O.V. Kovalenko, V.Yu. Vorovsky, O.V. Khmelenko, O.I. Kushnerov, Effect of short-term heat treatment in the hydrogen on magnetic properties of ZnO:Mn nanocrystals, Journal Physics and Chemistry of Solid State, 23 (3), 569 (2022); https://doi.org/10.15330/pcss.23.3.569-574.

E. V. Lavrov, F. Herklotz, and J. Weber, Identification of two hydrogen donors in ZnO, Phys. Rev. B 79, 165210 (2009); https://doi.org/10.1103/PhysRevB.79.165210.