Spectroscopic studies of magnon excitations in nanosized NiO

Nina Mironova-Ulmane 1Alexei Kuzmin 1Ints Steins 2Janis Grabis 2Ilmo Sildos 3Martti Pärs 3

1. Institute of Solid State Physics, University of Latvia, 8 Kengaraga, Riga LV-1063, Latvia
2. Institute of Inorganic Chemistry, Riga Technical University, Riga LV-2169, Latvia
3. Institute of Physics, University of Tartu, Riia str. 142, Tartu 51014, Estonia


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 NicMg1−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.


[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).


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium A, by Nina Mironova-Ulmane
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-11 11:23
Revised:   2009-06-07 00:44