Magnetism in Mn-doped ZnO bulk samples prepared by solid state reaction

Abstract

Contrasting magnetic properties were obtained from bulk Mn-doped ZnO synthesized under different processing conditions. While a ferrimagnetic phase transition was observable in a Zn0.95Mn0.05O sample processed at 1170 K, no such transition was found for a sample with the same composition processed at 1370 K. The detailed magnetic, structural, and spectroscopic studies of these two samples have revealed that the ferrimagnetic transition in the former sample is attributable to the secondary phase, (Mn,Zn)Mn2O4, in the system. For the latter sample processed at higher temperature, no secondary phase was detected and the major feature of the system remained paramagnetic down to 4 K. The implication of the present results for Mn-doped ZnO thin films is discussed.

Co-Precipitation Synthesis and Characterization of Nanocrystalline Zinc Oxide Particles Doped with Cu<sup>2+</sup> Ions

“…Room temperature ferromagnetism has indeed been reported in many of transition metal-doped ZnO. However, the origin of ferromagnetism in transition metaldoped oxide semiconductors remain controversial, some report claims that the room temperature ferromagnetism in TM-doped oxides might come from precipitation of magnetic cluster or secondary magnetic phases [7,8], while others claims that ferromagnetic ordering is intrinsic [9]. Motivated by these contradictory results, experimental studies have addressed the magnetic properties of Cu-doped, since it is known that the metallic Cu as well as all possible Cu-based oxide such as Cu 2 O or CuO is nonmagnetic [10].…”

Defect-mediated ferromagnetism in ZnO:Mn nanorods

“…However, there are some experimental works reported on ZnO:Mn with various morphologies, such as bulk [9], thin films [10] and nanoparticles [11] where the magnetism is very sensitive to preparation conditions such as synthesis method, doping content, sintering temperature and annealing environment. For example, Zn 0.99 Mn 0.01 O bulk samples prepared by a standard solid-state reaction method exhibited room-temperature ferromagnetism when sintered at a temperature of 500 °C; however, the samples sintered at a higher temperature of 900 °C displayed a linear response, showing a paramagnetic behavior [12].…”

Magnetic and optical properties of single crystals of transition metal doped ZnO

“…Since the prediction of room temperature ferromagnetism within the wide bandgap semiconductors, numerous attempts have been made to produce these materials. This has resulted in a number of reports of ferromagnetism in the Zn 1-x Mn x O and Zn 1-x Co x O materials systems by numerous production methods, including pulsed laser deposition [1][2][3] [4,5], molecular beam epitaxy [6], and solid state reaction [7,8]. The results to date are still somewhat controversial and a convergent picture of the processing techniques and criteria to routinely and reliably obtain room temperature ferromagnetism are as of yet.…”