Crystalline Ni nanoparticles as the origin of ferromagnetism in Ni implanted ZnO crystals

Zhou, Shengqiang; Potzger, К.; Zhang, Gufei; Eichhorn, F.; Skorupa, W.; Helm, M.; Faßbender, J.

doi:10.1063/1.2396763

Cited by 51 publications

(43 citation statements)

References 29 publications

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“…In some cases, the observed room temperature ferromagnetism (RTFM) was claimed to be carrier mediated [19,23] or occurring due to defects [22] or oxygen vacancies [24][25][26]. Still in a few other cases, Ni clusters were responsible for observed RTFM [27][28][29]. It is also reported that homogeneous incorporation of Ni in ZnO results in paramagnetic samples, whereas the imperfectly doped samples lead to ferromagnetism [30].…”

Section: Introductionmentioning

confidence: 95%

Investigations of DC-magnetization behavior of nanocrystalline ZnO:Ni

Goyal

Bhatti

Chaudhary

2010

Journal of Alloys and Compounds

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Section: Introductionmentioning

confidence: 95%

Investigations of DC-magnetization behavior of nanocrystalline ZnO:Ni

Goyal

Bhatti

Chaudhary

2010

Journal of Alloys and Compounds

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“…These kinds of materials are fabricated by doping oxide semiconductors, such as ZnO, TiO 2 , SnO 2 , and In 2 O 3 , with transition metals. Many groups have reported the observation of ferromagnetism in transition-metal-doped rutile and anatase TiO 2 [1][2][3][4]. However, the origin for the measured ferromagnetism is questionable.…”

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confidence: 91%

Investigation of structural and magnetic properties of Ni implanted rutile

Ding

2012

Sci. China Phys. Mech. Astron.

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In this paper, the structural and magnetic properties of Ni metal implanted TiO 2 single crystals are discussed. Ni nanocrystals (NCs) have been formed in TiO 2 after ion implantation. Their crystalline sizes were increased with increasing post-annealing temperature. Metallic Ni NCs inside the TiO 2 matrix are stable up to an annealing temperature of 1073 K. The Ni NCs forming inside TiO 2 are the major contribution of the measured ferromagnetism. diluted magnetic oxides, ion implantation, TiO 2 PACS number(s): 78.67. Bf, 61.05.Cp, 82.80.Yc Citation: Ding B F. Investigation of structural and magnetic properties of Ni implanted rutile.Currently, there is a great deal of interest in diluted magnetic oxides (DMO), because the ferromagnetism is robust well above room temperature. These kinds of materials are fabricated by doping oxide semiconductors, such as ZnO, TiO 2 , SnO 2 , and In 2 O 3 , with transition metals. Many groups have reported the observation of ferromagnetism in transition-metal-doped rutile and anatase TiO 2 [1-4]. However, the origin for the measured ferromagnetism is questionable. It was also found that the measured ferromagnetic properties can originate from nanoscale precipitates [5-10], or defects inside TiO 2 [11-13]. Akdogan et al. [14] identified two ferromagnetic contributions in Co implanted TiO 2 from diluted Co 2+ and metallic Co nanocrystals (NCs), respectively. Recently several review articles have addressed the complexity of transition-metal-doped oxides concerning the origin of ferromagnetism [15-17]. At the same time, there are some reports about Fe-doped, TiO 2 , Co-doped, TiO 2 , La or Sr-doped, TiO 2 [ 7,18,19]. In those papers, the authors observed the ferromagnetic NCs and pronounced magnetoelectric effects. To optimize these magnetoelectric effects, a systematic investigation of structure, magnetic properties and temperature stability of these NCs is needed. In this article, a correlation between structure and magnetism in Ni-implanted TiO 2 is presented. We try to answer two questions: (i) What is the origin of the ferromagnetism in Ni-implanted TiO 2 , and (ii) what is the effect of postannealing on the magnetic and structural properties of Ni-implanted TiO 2 ? ExperimentsCommercial TiO 2 bulk crystals were implanted with Ni ions at 623 K with a fluence of 4×10 16 cm 2 . The implantation energy was 180 keV, which resulted in a projected range of R P =(84±29) nm and a maximum atomic concentration of about 5% (TRIM code). Annealing was performed in a high-vacuum (base pressure 10 6 mbar) furnace at temperatures ranging from 823 to 1073 K for 15 min. Four samples were investigated and are listed in Table 1. The lattice damage recovered after annealing was evaluated by Rutherford backscattering/channeling spectrometry (RBS/C).

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“…Temperature dependent magnetization was measured after zero field cooling and field cooling (ZFC/FC) [31]. Note that SQUID magnetometry is an integral method, which measures the total magnetic response from the sample, including substrate and possible contaminations from previous processing [43,44].…”

Section: Experimental Methodsmentioning

confidence: 99%

Ferromagnetic transition metal implanted ZnO: A diluted magnetic semiconductor?

Zhou

Potzger

et al. 2009

Vacuum

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Recently theoretical works predict that some semiconductors (e.g. ZnO) doped with magnetic ions are diluted magnetic semiconductors (DMS). In DMS magnetic ions substitute cation sites of the host semiconductor and are coupled by free carriers resulting in ferromagnetism. One of the main obstacles in creating DMS materials is the formation of secondary phases because of the solid-solubility limit of magnetic ions in semiconductor host. In our study transition metal ions were implanted into ZnO single crystals with the peak concentrations of 0.5-10 at.%. We established a correlation between structural and magnetic properties. By synchrotron radiation X-ray diffraction (XRD) secondary phases

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Crystalline Ni nanoparticles as the origin of ferromagnetism in Ni implanted ZnO crystals

Cited by 51 publications

References 29 publications

Investigations of DC-magnetization behavior of nanocrystalline ZnO:Ni

Investigations of DC-magnetization behavior of nanocrystalline ZnO:Ni

Investigation of structural and magnetic properties of Ni implanted rutile

Ferromagnetic transition metal implanted ZnO: A diluted magnetic semiconductor?

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