Structural and magnetic properties of chemically synthesized Fe doped ZnO

Kumar, Shalendra; Kim, Y. J.; Koo, Bon Heun; Sharma, S. K.; Vargas, J. M.; Knobel, M.; Gautam, Sanjeev; Chae, Keun Hwa; Kim, D. K.; Kim, Y. K.; Lee, C. G.

doi:10.1063/1.3073933

Cited by 70 publications

(18 citation statements)

References 20 publications

(17 reference statements)

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“…Similar results have been detected in other Zn 0.95 − x Fe 0.05 Na x O (x = 0, 0.01, 0.05) samples. Based on the XPS results, Fe chemical states in Zn 0.95 − x Fe 0.05 Na x O samples are believed to be Fe 2+ as substitution state, similar to the reports on the ZnFeO system by other studies [27,28], which reveals that the chemical state of Fe in Fe doped ZnO changes from Fe 3+ to Fe 2+ with an increase in the amount of Fe dopant and Fe chemical states in Zn 1 − x Fe x O (x ≥ 2.6 at.%) are found to be Fe 2+ . Fig.…”

Section: Resultssupporting

confidence: 76%

Defect-induced room temperature ferromagnetism in Fe and Na co-doped ZnO nanoparticles

Jiang

Yan

2012

Journal of Alloys and Compounds

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Section: Resultssupporting

confidence: 76%

Defect-induced room temperature ferromagnetism in Fe and Na co-doped ZnO nanoparticles

Jiang

Yan

2012

Journal of Alloys and Compounds

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“…Such a shift in XRD with Cu doping has been reported in literature by Tiwari et al 12 for Cu doped ZnO thin films and assumed to be an additional evidence for Cu occupying the Zn sites in ZnO matrix. Moreover, the HR-TEM and SAED pattern (due to the brevity of article, not shown here) also indicate that there is no formation of nano [10][11][12][13] In the present case, this observed magnetic behavior may be explained in the light of BMP model. The NEXAFS measurements performed at Cu K -edge clearly indicate that Cu has 3d 9 electronic configuration, therefore, the FM may results due to the Cu doping as well as defects.…”

mentioning

confidence: 51%

ROOM TEMPERATURE FERROMAGNETISM IN PURE AND Cu DOPED ZnO NANORODS: ROLE OF COPPER OR DEFECTS

Kumar

Koo

Lee

et al. 2011

Funct. Mater. Lett.

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We report structural, magnetic and electronic structure studies of pure and Cu doped ZnO nanorods with the aim to understand the origin of ferromagnetism. A structural study indicates that all the samples exhibit single phase nature and rules out the formation of secondary phase. NEXAFS measurements reveal that Cu ions exist in Cu 2+ state. Magnetic hysteresis loop measurements reflect that the pure and Cu doped ZnO nanorods exhibit room temperature ferromagnetism. The increase in the intensity of green emission in photoluminescence study indicates that defects density increases with Cu doping.In the recent years dilute magnetic semiconductors (DMS) has attracted the interest of researchers due to their potential application in spintronics devices. 1-3 Initially, it was assumed that DMS and their properties can be tailored by partial replacement of cations in semiconducting host matrix via transition metal (TM) cations. But the discovery of the unexpected magnetism in HfO 2 , 4 TiO 2 , 5 ZnO, 6 etc. has triggered a debate on the origin of ferromagnetism in the DMS. Several experimental as well as theoretical groups have reported the origin of ferromagnetism in the nanoparticles or thin films of diamagnetic oxides. Though, among the diamagnetic oxides showing the d 0 ferromagnetism, zinc oxide (ZnO) has been recognized as one of the most important materials for the application in the multifunctional devices because of its various properties.Even though ferromagnetism has been observed in a number of systems, experimental studies on TM doped ZnO have produced inconsistent results and the mechanism of * , † Corresponding Authors. ferromagnetism (FM) in TM doped ZnO remains unclear. It is considered that the TM dopants in ZnO form clusters or secondary phase, therefore, having many controversies about whether the observed FM is an intrinsic or extrinsic property of the material. These facts motivated us to study the FM in Cu doped ZnO. As it is well known that Cu is a potential magnetic ion only in +2 state with +1/2 spin and neither metallic Cu nor its oxide (CuO and Cu 2 O) is ferromagnetic. In these circumstances, Cu doped ZnO has potential of showing magnetic behavior at RT because FM observed in Cu based system will undoubtedly be the intrinsic property of the material. Despite the above fact, Cu doped ZnO system is not far away from controversies. There are many contradictory reports in which some authors confirmed the presence of FM in this system whereas others ruled out same. 7-10 These controversial results indicate that FM in DMSs is very sensitive to preparation method and conditions.In this letter, we have reported room temperature ferromagnetism in Cu doped ZnO synthesized by co-precipitation 17 Funct. Mater. Lett. 2011.04:17-20. Downloaded from www.worldscientific.com by PENNSYLVANIA STATE UNIVERSITY on 03/14/15. For personal use only.

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“…It was used for the samples obtained by sintering of conventional [30,37,44,48–52 54–55 58,64] or nanopowders [24,29,32,41–42 46,53,56,59,65–66], or for films obtained by sol–gel method, pyrolysis, CVD or PLD [22–23 25,27–28 45]. If the samples mentioned in the analysed papers were not poreless, such as in the partly sintered powders (open and filled diamonds) [29,32,37,44,50,52–53 56,59,62,65], nanorods, or nanowires (open and filled down-triangles) [34,43,57,61], we introduced the additional porosity coefficient, p , for the s GB . p varies from 0 for nonsintered powders to 1 for the fully compacted polycrystals.…”

Section: Discussionmentioning

confidence: 99%

Ferromagnetic behaviour of Fe-doped ZnO nanograined films

Straumal¹,

Protasova²,

Мазилкин³

et al. 2013

Beilstein J. Nanotechnol.

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SummaryThe influence of the grain boundary (GB) specific area s GB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area s GB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if s GB is higher than a certain threshold value s th = 5 × 104 m2/m3. It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom %) have been investigated. The films were deposited by using the wet chemistry “liquid ceramics” method. The samples demonstrate ferromagnetic behaviour with J s up to 0.10 emu/g (0.025 μB/f.u.ZnO) and coercivity H c ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic “grain boundary foam” responsible for the magnetic properties of pure and doped ZnO.

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Structural and magnetic properties of chemically synthesized Fe doped ZnO

Cited by 70 publications

References 20 publications

Defect-induced room temperature ferromagnetism in Fe and Na co-doped ZnO nanoparticles

Defect-induced room temperature ferromagnetism in Fe and Na co-doped ZnO nanoparticles

ROOM TEMPERATURE FERROMAGNETISM IN PURE AND Cu DOPED ZnO NANORODS: ROLE OF COPPER OR DEFECTS

Ferromagnetic behaviour of Fe-doped ZnO nanograined films

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