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Luo X, Tseng LT, Lee WT, Tan TT, Bao NN, Liu R, Ding J, Li S, Lauter V, Yi JB. Probing the magnetic profile of diluted magnetic semiconductors using polarized neutron reflectivity. Sci Rep 2017; 7:6341. [PMID: 28740239 PMCID: PMC5524716 DOI: 10.1038/s41598-017-06793-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/16/2017] [Indexed: 11/09/2022] Open
Abstract
Room temperature ferromagnetism has been observed in the Cu doped ZnO films deposited under an oxygen partial pressure of 10-3 and 10-5 torr on Pt (200 nm)/Ti (45 nm)/Si (001) substrates using pulsed laser deposition. Due to the deposition at relatively high temperature (873 K), Cu and Ti atoms diffuse to the surface and interface, which significantly affects the magnetic properties. Depth sensitive polarized neutron reflectometry method provides the details of the composition and magnetization profiles and shows that an accumulation of Cu on the surface leads to an increase in the magnetization near the surface. Our results reveal that the presence of the copper at Zn sites induces ferromagnetism at room temperature, confirming intrinsic ferromagnetism.
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Affiliation(s)
- X Luo
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - L T Tseng
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - W T Lee
- Bragg Institute, ANSTO, New Illawarra Road, Lucas Heights, NSW, 2234, Australia
| | - T T Tan
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - N N Bao
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore, Singapore
| | - R Liu
- SIMS Facility, Office of the Deputy-Vice Chancellor (Research and Development), Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - J Ding
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore, Singapore
| | - S Li
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - V Lauter
- Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
| | - J B Yi
- School of Materials Science and Engineering, UNSW, Sydney, NSW, 2052, Australia.
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Saadaoui H, Luo X, Salman Z, Cui XY, Bao NN, Bao P, Zheng RK, Tseng LT, Du YH, Prokscha T, Suter A, Liu T, Wang YR, Li S, Ding J, Ringer SP, Morenzoni E, Yi JB. Intrinsic Ferromagnetism in the Diluted Magnetic Semiconductor Co:TiO_{2}. Phys Rev Lett 2016; 117:227202. [PMID: 27925730 DOI: 10.1103/physrevlett.117.227202] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Indexed: 06/06/2023]
Abstract
Here we present a study of magnetism in Co_{0.05}Ti_{0.95}O_{2-δ} anatase films grown by pulsed laser deposition under a variety of oxygen partial pressures and deposition rates. Energy-dispersive spectrometry and transmission electron microscopy analyses indicate that a high deposition rate leads to a homogeneous microstructure, while a very low rate or postannealing results in cobalt clustering. Depth resolved low-energy muon spin rotation experiments show that films grown at a low oxygen partial pressure (≈10^{-6} torr) with a uniform structure are fully magnetic, indicating intrinsic ferromagnetism. First principles calculations identify the beneficial role of low oxygen partial pressure in the realization of uniform carrier-mediated ferromagnetism. This work demonstrates that Co:TiO_{2} is an intrinsic diluted magnetic semiconductor.
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Affiliation(s)
- H Saadaoui
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - X Luo
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - Z Salman
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - X Y Cui
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - N N Bao
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore
| | - P Bao
- School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - R K Zheng
- School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - L T Tseng
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - Y H Du
- Institute of Chemical and Engineering Science, Agency for Science, Technology and Research (A*STAR), 1 Pesek Road, Jurong Island, 627833, Singapore
| | - T Prokscha
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - A Suter
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - T Liu
- ANKA, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Y R Wang
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - S Li
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
| | - J Ding
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore
| | - S P Ringer
- School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales 2006, Australia
- The Australian Institute for Nanoscale Science and Technology, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - E Morenzoni
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - J B Yi
- School of Materials Science and Engineering, UNSW, Sydney, New South Wales 2052, Australia
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Rusydi A, Dhar S, Barman AR, Qi DC, Motapothula M, Yi JB, Santoso I, Feng YP, Yang K, Dai Y, Yakovlev NL, Ding J, Wee ATS, Neuber G, Breese MBH, Ruebhausen M, Hilgenkamp H, Venkatesan T. Cationic-vacancy-induced room-temperature ferromagnetism in transparent, conducting anatase Ti1-xTaxO2 (x~0.05) thin films. Philos Trans A Math Phys Eng Sci 2012; 370:4927-4943. [PMID: 22987036 DOI: 10.1098/rsta.2012.0198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report room-temperature ferromagnetism (FM) in highly conducting, transparent anatase Ti(1-x)Ta(x)O(2) (x∼0.05) thin films grown by pulsed laser deposition on LaAlO(3) substrates. Rutherford backscattering spectrometry (RBS), X-ray diffraction, proton-induced X-ray emission, X-ray absorption spectroscopy (XAS) and time-of-flight secondary-ion mass spectrometry indicated negligible magnetic contaminants in the films. The presence of FM with concomitant large carrier densities was determined by a combination of superconducting quantum interference device magnetometry, electrical transport measurements, soft X-ray magnetic circular dichroism (SXMCD), XAS and optical magnetic circular dichroism, and was supported by first-principles calculations. SXMCD and XAS measurements revealed a 90 per cent contribution to FM from the Ti ions, and a 10 per cent contribution from the O ions. RBS/channelling measurements show complete Ta substitution in the Ti sites, though carrier activation was only 50 per cent at 5 per cent Ta concentration, implying compensation by cationic defects. The role of the Ti vacancy (V(Ti)) and Ti(3+) was studied via XAS and X-ray photoemission spectroscopy, respectively. It was found that, in films with strong FM, the V(Ti) signal was strong while the Ti(3+) signal was absent. We propose (in the absence of any obvious exchange mechanisms) that the localized magnetic moments, V(Ti) sites, are ferromagnetically ordered by itinerant carriers. Cationic-defect-induced magnetism is an alternative route to FM in wide-band-gap semiconducting oxides without any magnetic elements.
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Affiliation(s)
- A Rusydi
- NUSNNI-NanoCore, National University of Singapore, Republic of Singapore.
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Ma YW, Ding J, Liu WS, Yi JB, Ng CM, Bao NN, Huang XL. Structural and magnetic properties of ZnO nanocrystals in (Zn, Al)O films using pulse laser deposition. J Nanosci Nanotechnol 2011; 11:2628-2631. [PMID: 21449441 DOI: 10.1166/jnn.2011.2729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this manuscript, we reported that the room temperature ferromagnetism was observed in (Zn0.70, Al0.30)O film, which was fabricated by a novel physical method (pulse laser deposition (PLD)). The film was deposited from (Zn0.80, Al0.20)O ceramic target onto quartz (110) substrate by PLD at 400 degrees C under an oxygen partial pressure of 10(-4) torr. TEM result shows ZnO NCs with diameter of 4-5 nm and they are quite uniformly embedded into amorphous ZnO-Al2O3 phase. The SAED shows clearly that ZnO NCs possess polycrystalline structure. The SQUID measurement shows that the film has room temperature ferromagnetism (saturation magnetization = 3.6 emu/cm3) with Curie temperature above 300 K. The magnitude of magnetic moment of the films can be changed by tuning ZnO NCs size. Both oxygen partial pressure and film thickness studies show that the origin of ferromagnetism is possibly related to the oxygen defects at the surface of ZnO NCs.
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Affiliation(s)
- Y W Ma
- Department of Materials Science and Engineering, National University of Singapore, Singapore 119260, Singapore
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Wang BM, Liu Y, Ren P, Xia B, Ruan KB, Yi JB, Ding J, Li XG, Wang L. Large exchange bias after zero-field cooling from an unmagnetized state. Phys Rev Lett 2011; 106:077203. [PMID: 21405539 DOI: 10.1103/physrevlett.106.077203] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Indexed: 05/30/2023]
Abstract
Exchange bias (EB) is usually observed in systems with an interface between different magnetic phases after field cooling. Here we report an unusual phenomenon in which a large EB can be observed in Ni-Mn-In bulk alloys after zero-field cooling from an unmagnetized state. We propose that this is related to the newly formed interface between different magnetic phases during the initial magnetization process. The magnetic unidirectional anisotropy, which is the origin of the EB effect, can be created isothermally below the blocking temperature.
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Affiliation(s)
- B M Wang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
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Ariando, Wang X, Baskaran G, Liu ZQ, Huijben J, Yi JB, Annadi A, Barman AR, Rusydi A, Dhar S, Feng YP, Ding J, Hilgenkamp H, Venkatesan T. Electronic phase separation at the LaAlO3/SrTiO3 interface. Nat Commun 2011; 2:188. [DOI: 10.1038/ncomms1192] [Citation(s) in RCA: 347] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 01/12/2010] [Indexed: 11/09/2022] Open
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Herng TS, Qi DC, Berlijn T, Yi JB, Yang KS, Dai Y, Feng YP, Santoso I, Sánchez-Hanke C, Gao XY, Wee ATS, Ku W, Ding J, Rusydi A. Room-temperature ferromagnetism of Cu-doped ZnO films probed by soft X-ray magnetic circular dichroism. Phys Rev Lett 2010; 105:207201. [PMID: 21231259 DOI: 10.1103/physrevlett.105.207201] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Indexed: 05/30/2023]
Abstract
We report direct evidence of room-temperature ferromagnetic ordering in O-deficient ZnO:Cu films by using soft x-ray magnetic circular dichroism and x-ray absorption. Our measurements have revealed unambiguously two distinct features of Cu atoms associated with (i) magnetically ordered Cu ions present only in the oxygen-deficient samples and (ii) magnetically disordered regular Cu2+ ions present in all the samples. We find that a sufficient amount of both oxygen vacancies (V(O)) and Cu impurities is essential to the observed ferromagnetism, and a non-negligible portion of Cu impurities is uninvolved in the magnetic order. Based on first-principles calculations, we propose a microscopic "indirect double-exchange" model, in which alignments of localized large moments of Cu in the vicinity of the V(O) are mediated by the large-sized vacancy orbitals.
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Affiliation(s)
- T S Herng
- Department of Materials Science and Engineering, National University of Singapore, 7 Engineering Drive 1, Singapore 117574, Singapore
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Yi JB, Lim CC, Xing GZ, Fan HM, Van LH, Huang SL, Yang KS, Huang XL, Qin XB, Wang BY, Wu T, Wang L, Zhang HT, Gao XY, Liu T, Wee ATS, Feng YP, Ding J. Ferromagnetism in dilute magnetic semiconductors through defect engineering: Li-doped ZnO. Phys Rev Lett 2010; 104:137201. [PMID: 20481907 DOI: 10.1103/physrevlett.104.137201] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 01/07/2010] [Indexed: 05/26/2023]
Abstract
We demonstrate, both theoretically and experimentally, that cation vacancy can be the origin of ferromagnetism in intrinsic dilute magnetic semiconductors. The vacancies can be controlled to tune the ferromagnetism. Using Li-doped ZnO as an example, we found that while Li itself is nonmagnetic, it generates holes in ZnO, and its presence reduces the formation energy of Zn vacancy, and thereby stabilizes the zinc vacancy. Room temperature ferromagnetism with p type conduction was observed in pulsed laser deposited ZnO:Li films with certain doping concentration and oxygen partial pressure.
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Affiliation(s)
- J B Yi
- Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore.
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Affiliation(s)
- S. Thongmee
- a Department of Materials Science and Engineering , National University of Singapore , Singapore
| | - J. Ding
- a Department of Materials Science and Engineering , National University of Singapore , Singapore
| | - Y. Jiabao
- a Department of Materials Science and Engineering , National University of Singapore , Singapore
| | - H. Pan
- b Department of Physics , National University of Singapore , Singapore
| | - J. B. Yi
- a Department of Materials Science and Engineering , National University of Singapore , Singapore
| | - J. Y. Lin
- b Department of Physics , National University of Singapore , Singapore
- c Institute of Chemical and Engineering Sciences , Singapore
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Pan H, Yi JB, Shen L, Wu RQ, Yang JH, Lin JY, Feng YP, Ding J, Van LH, Yin JH. Room-temperature ferromagnetism in carbon-doped ZnO. Phys Rev Lett 2007; 99:127201. [PMID: 17930547 DOI: 10.1103/physrevlett.99.127201] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 01/19/2007] [Indexed: 05/25/2023]
Abstract
We report ferromagnetism in carbon-doped ZnO. Our first-principles calculations based on density functional theory predicted a magnetic moment of 2.02 mu(B) per carbon when carbon substitutes oxygen in ZnO, and an ferromagnetic coupling among magnetic moments of the carbon dopants. The theoretical prediction was confirmed experimentally. C-doped ZnO films deposited by pulsed-laser deposition showed ferromagnetism with Curie temperatures higher than 400 K. The measured magnetic moment based on the content of carbide in the films [(1.5-3.0) mu(B) per carbon] was in agreement with the theoretical prediction. The magnetism is due to the Zn-C system in the ZnO environment.
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Affiliation(s)
- H Pan
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542
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Choi JH, Choi JH, Kim DY, Yoon JH, Youn HY, Yi JB, Rhee HI, Ryu KH, Jung K, Han CK, Kwak WJ, Cho YB. Effects of SKI 306X, a new herbal agent, on proteoglycan degradation in cartilage explant culture and collagenase-induced rabbit osteoarthritis model. Osteoarthritis Cartilage 2002; 10:471-8. [PMID: 12056850 DOI: 10.1053/joca.2002.0526] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Protective effects of SKI 306X, a natural herbal product extracted from three herbs Clematis mandshurica, Trichosanthes kirilowii, and Prunella vulgaris, on articular cartilage was examined and compared with other osteoarthritis (OA) drugs using in vitro and in vivo models. METHODS In vitro culture of rabbit articular cartilage explants was used as a model to measure the effects of drugs on the matrix degradation. The recombinant human interleukin-1alpha (rhIL-1alpha, 5 ng/ml) was added to induce proteoglycan (PG) degradation and the degree of PG degradation was assessed by measuring the amount of glycosaminoglycan (GAG) released into the culture medium. In in vivo experiment, collagenase was intraarticularly injected twice into the right knee joint of rabbits to induce OA-like change, and test agents were orally administered once a day for 28 days. The degrees of OA-like changes were evaluated through a histological examination. RESULTS In vitro study revealed SKI 306X inhibited the degradation of PG in a concentration-dependent manner. Trichosanthes kirilowii, which is one of the major components of SKI 306X, also significantly inhibited the GAG release in cartilage explant culture at 0.3 and 0.1 mg/ml. Dexamethasone and NSAIDs, such as diclofenac and rofecoxib, had no significant effects on the suppression of PG degradation. In in vivo studies, OA-like degeneration of the articular cartilage and synovial tissue was induced by injecting collagenase into the right knee joint of mature rabbits. At a dose of 200 mg/kg, SKI 306X reduced the OA-like histological changes, whereas diclofenac had no effect at 10 mg/kg. CONCLUSION These results indicate that SKI 306X inhibited PG degradation in cartilage explant culture, and its prophylactic administration significantly protected the knee joint of rabbit from OA-like change in collagenase-induced experimental OA model. This strongly suggests that SKI 306X can be a good OA agent with some cartilage protection activity.
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Affiliation(s)
- J-H Choi
- College of Veterinary Medicine, School of Agricultural Biotechnology, Seoul National University, 103 Seodun-Dong, Suwon 441-744, Korea
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Wang X, Yi JB. [A survey of the prevalence of oral disease in 204 old people]. Shanghai Kou Qiang Yi Xue 2001; 10:245. [PMID: 14994007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- X Wang
- Stomatological Hospital of Tai'an City, Tai'an 271000 Shandong province, China
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