The Influence of Doping with Transition Metal Ions on the Structure and Magnetic Properties of Zinc Oxide Thin Films

Jenica Neamtu,Marius Volmer

doi:10.1155/2014/265969

Abstract

Zn1−xNixO (x = 0.03 ÷ 0.10) and Zn1−xFexO (x = 0.03 ÷ 0.15) thin films were synthesized by sol-gel method. The structure and the surface morphology of zinc oxide thin films doped with transition metal (TM) ions have been investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). The magnetic studies were done using vibrating sample magnetometer (VSM) at room temperature. Experimental results revealed that the substitution of Ni ions in ZnO wurtzite lattice for the contents x = 0.03 ÷ 0.10 (Ni2+) leads to weak ferromagnetism of thin films. For Zn1−xFexO with x = 0.03 ÷ 0.05, the Fe3+ ions are magnetic coupling by superexchange interaction via oxygen ions in wurtzite structure. For x = 0.10 ÷ 0.15 (Fe3+) one can observe the increasing of secondary phase of ZnFe2O4 spinel. The Zn0.9Fe0.1O film shows a superparamagnetic behavior due to small crystallite sizes and the net spin magnetic moments arisen from the interaction between the iron ions through an oxygen ion in the spinel structure.

Highlights

Since the study of III–V semiconductors doped with transition metals by Ohno [1, 2], many researches were conducted to obtain the room temperature ferromagnetism of diluted magnetic semiconductors (DMS)
Ferromagnetism in transition metal (TM)-doped ZnO is theoretically investigated by Sato and Katayama-Yoshida [3] using ab initio calculations based on local density approximation (LDA)
X-ray diffraction intensity distribution it is observed that the peaks of wurtzite structure are majorities, indicating that these thin films have a structure similar to ZnO, in agreement with the reported JCPDS card no. 36-1451

Summary

Introduction

Since the study of III–V semiconductors doped with transition metals by Ohno [1, 2], many researches were conducted to obtain the room temperature ferromagnetism of diluted magnetic semiconductors (DMS). A few years ago, it turned out that most of incomplete 3d shell metal ions can be used to produce room temperature magnetism in ZnO doped with transition metal (Cu, Mn, Fe, Co, or Ni) [4,5,6,7,8,9]. It is a great interest because the DMS can be integrated for fabricating transparent spinbased devices [10].

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Conclusion