Magnon excitations in pure nickel oxide (NiO) were successfully probed in the past by Raman spectroscopy [1,2]. Recently we have extended these studies to Ni_cMg_1−cO solid solutions [3,4], where unpredicted behavior of temperature and composition dependences of one-magnon excitation energies has been observed.

In this work, we present the Raman scattering in nanosized NiO powders, produced by the plasma synthesis [5]. Single-crystal NiO, grown by the method of chemical transport reactions on MgO(100) substrate, was also used for comparison. Raman experiments were conducted in a wide range of temperatures from 10 to 300 K.

The Raman spectrum of single-crystal NiO shows several bands in the probed region above 400 cm^-1. The first four bands have vibrational origin and, according to assignment in [3], correspond to one-phonon (1P) TO and LO modes (at ~570 cm^-1), two-phonon (2P) 2TO modes (at ~730 cm^-1), TO + LO (at ~906 cm^-1) and 2LO (at ~1090 cm^-1) modes. The last strongest band at 1490 cm^-1 is due to a two-magnon (2M) scattering. It was observed that the intensity of two-magnon band decreases rapidly in nano-sized NiO. This effect is attributed to a decrease of antiferromagnetic spin correlations and leads to the antiferromagnetic-to-paramagnetic phase transition.

References:

[1] R. E. Dietz, G. I. Parisot, A. E. Meixner, Phys. Rev. B 4, 2302 (1971).

[2] M. Grimsditch, L. E. McNeil, D. J. Lockwood, Phys. Rev. B 58, 14462 (1998).

[3] E. Cazzanelli, A. Kuzmin, G. Mariotto, N. Mironova-Ulmane, J. Phys.: Condens. Matter 15, 2045 (2003).

[4] E. Cazzanelli, A. Kuzmin, G. Mariotto, N. Mironova-Ulmane, Phys. Rev. B 71, 1344151 (2005).

[5] J. Grabis, I. Steins, D. Rasmane, G. Heidemane, J. European Ceramic Soc. 17, 1437 (1997).

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/11273 must be provided.

1. Comparison of RE ion luminescence in zirconia nanocrystals and Single crystals
2. Nanostructural characterization and magnetic properties of pure and Fe, Co or Mn-doped TiO₂ nanopowders prepared by Solar Physical Vapor Deposition (SPVD)
3. Phase development and properties of high-temperature ceramic in the system mullite-ZrO₂
4. Fast luminescence in ZnO structures
5. Concentration dependence of Ni²⁺ luminescence in MgO
6. Preparation of Silicon Carbide/Nitride Nanocomposites with Oxides or Nitrides