Effect of 50 MeV Li⁺³ ion beam irradiation on structural and magnetic properties of Zn_0.96 Mn_0.04 O powder

Abstract

The present work aims to study the effect of 50 MeV Li⁺³ ion beam irradiation on the structural, morphological and magnetic properties of Zn_0.96Mn_0.04O samples. Zn_0.96Mn_0.04O samples were synthesized by solid-state reaction technique. The samples exhibit impurity phase and upon irradiation it disappears. Rietveld refinement analysis indicates that the substitutional incorporation of Mn in the host lattice increases with irradiation. Field-dependent magnetization (M–H) measurement explicitly indicates ferromagnetic nature of the samples at room temperature. The variation observed in temperature-dependent magnetization (M–T) measurement (500 Oe) indicates that ferromagnetism in the system seems to be mainly intrinsic, though superparamagnetic Mn nanoparticles also has a minor role. The analysis of M–T data at comparatively high field (5000 Oe) provides an estimation of antiferromagnetic exchange, which acts as a reducing agent for observed magnetic moment. The value of saturation magnetization has been increased upon irradiation.

Keywords:

• Mn-doped ZnO
• heavy ion irradiation
• defects
• metallic oxides
• ferromagnetism

PACS:

• 81.05. Dz
• 61.80. Jh
• 61.72.J-
• 75.50.Pp

Acknowledgements

This work is financially supported by DST-Government of India, IUAC-New Delhi, and CRNN-University of Calcutta via project nos: SR/FTP/PS-31/2006, UFUP-43308, and Conv/002/Nano RAC (2008), respectively. The author S.K.N. is thankful to UGC for providing his fellowship. We acknowledge Department of Chemical Technology-University of Calcutta, UGC-DAE CSR-Indore, and IUAC-New Delhi to use their SEM, magnetic measurement, and pelletron facilities, respectively. We also acknowledge CRNN-University of Calcutta for the magnetic measurement of few irradiated samples by SQUID VSM.