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Atomic-scale study of the amorphous-to-crystalline phase transition mechanism in GeTe thin films
/ IS578 Collaboration
The underlying mechanism driving the structural amorphous-to-crystalline transition in Group VI chalcogenides is still a matter of debate even in the simplest GeTe system. We exploit the extreme sensitivity of 57Fe emission Mössbauer spectroscopy, following dilute implantation of 57Mn (T½ = 1.5 min) at ISOLDE/CERN, to study the electronic charge distribution in the immediate vicinity of the 57Fe probe substituting Ge (FeGe), and to interrogate the local environment of FeGe over the amorphous-crystalline phase transition in GeTe thin films. Our results show that the local structure of as-sputtered amorphous GeTe is a combination of tetrahedral and defect-octahedral sites. [...]
2017
- Published in : Sci.Rep. 7 (2017) 8234
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Atomic-Scale Magnetic Properties of Truly 3d-Diluted ZnO
/ Mantovan, Roberto (IMM-CNR, Agrate Brianza,Italy) ; Gunnlaugsson, Haraldur Páll (Leuven U. ; Aarhus U.) ; Johnston, Karl (CERN) ; Masenda, Hilary (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Mølholt, Torben Esmann (Iceland U.) ; Naidoo, Deena (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Ncube, Mehluli (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Shayestehaminzadeh, Seyedmohammad (Iceland U.) ; Bharuth-Ram, Krish (DUT, Durban ; iThemba LABS) ; Fanciulli, Marco (IMM-CNR, Agrate Brianza,Italy ; Milan Bicocca U.) et al.
In search for dilute magnetic semiconductors, the magnetic properties at the atomic-scale of Fe atoms incorporated in ZnO, in a concentration range of more than five orders of magnitude from $1 × 10^{−5}$ to 2.2 at% have been probed using emission 57 Fe Mössbauer spectroscopy on implanted $^{57}Mn$ and $^{57}Co$ produced at ISOLDE/CERN. In the ultra-dilute regime ($10 ^{−5}$ at%), the system shows isolated paramagnetic $Fe^{3+}$ ions with a spin–lattice type of relaxation. [...]
2015
- Published in : Advanced Electronic Materials 1 (2015) 1400039
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Interstitial Fe in MgO
/ Mølholt, T E (Iceland U.) ; Mantovan, R (IMM, Bologna) ; Gunnlaugsson, H P (Aarhus U.) ; Svane, A (Aarhus U.) ; Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Naidoo, D (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Bharuth-Ram, K (Durban-Westville U.) ; Fanciulli, M (IMM, Bologna ; Milan Bicocca U.) ; Gislason, H P (Iceland U.) ; Johnston, K (CERN) et al.
Isolated Fe-57 atoms were studied in MgO single-crystals by emission Mossbauer spectroscopy following implantation of Mn-57 decaying to Fe-57. Four Mossbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. [...]
2014
- Published in : J. Appl. Phys. 115 (2014) 023508
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Atomic scale properties of magnetic Mn-based alloys probed by emission Mössbauer spectroscopy
/ Mantovan, Roberto (Laboratorio MDM, IMM-CNR, Via Olivetti 2, I-20864 Agrate Brianza (MB), Italy) ; Gunnlaugsson, Haraldur Pall (Department of Physics and Astronomy, Aarhus University, DK-8000 Århus C, Denmark) ; Zenkevich, Andrei (NRC “Kurchatov Institute”, Moscow, Russian Federation) ; Zhao, Jianhua (State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, China) ; Plazaola, Fernando (Dpto. Electricidad y Electronica, Universidad del Pais Vasco (UPV/EHU), CP. 644, 48080 Bilbao, Spain) ; Johnston, Karl (-) ; Masenda, Hilary (School of Physics, University of the Witwatersrand, WITS 2050, South Africa) ; Mølholt, Torben (Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland) ; Naidoo, Deena (School of Physics, University of the Witwatersrand, WITS 2050, South Africa) ; Ncube, Masuli (School of Physics, University of the Witwatersrand, WITS 2050, South Africa) et al.
CERN-INTC-2013-028 ; INTC-P-388.
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2013.
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Paramagnetism in Mn/Fe implanted ZnO
/ Gunnlaugsson, HP (Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark.) ; Fanciulli, M (CNR IMM MDM Lab, I-20041 Agrate Brianza, MB, Italy. ; Univ Milano Bicocca, Dept Mat Sci, I-20125 Milan, Italy.) ; Weyer, G (Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark.) ; Kobayashi, Y (RIKEN, Inst Phys & Chem Res, Wako, Saitama 3510198, Japan.) ; Bharuth-Ram, K (Univ KwaZulu Natal, Sch Phys, ZA-4001 Durban, South Africa. ; iThemba Labs, ZA-7129 Somerset W, South Africa.) ; Olafsson, S (Univ Iceland, Inst Sci, IS-107 Reykjavik, Iceland.) ; Gislason, H P (Univ Iceland, Inst Sci, IS-107 Reykjavik, Iceland.) ; Gunnlaugsson, H P (Aarhus Univ, Dept Phys & Astron, DK-8000 Aarhus C, Denmark.) ; Yoshida, Y (Shizuoka Inst Sci & Technol, Shizuoka 4378555, Japan.) ; Langouche, G (Univ Louvain, Inst Kern En Stralings Fys, B-3001 Louvain, Belgium.) et al.
Prompted by the generally poor understanding of the nature of magnetic phenomena in 3d-metal doped ZnO, we have undertaken on-line Fe-57 Mossbauer spectroscopy on ZnO single crystals in an external magnetic field of 0.6 T, following the implantation of radioactive Mn-57 ions at room temperature. The Mossbauer spectra of the dilute Fe impurities are dominated by sextets whose angular dependence rules out an ordered magnetic state (which had been previously proposed) but are well accounted for on the basis of Fe3+ paramagnetic centers on substitutional Zn sites with unusually long relaxation times (> 20 ns) [...]
2010
- Published in : Appl. Phys. Lett. 97 (2010) 142501
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Temperature and dose dependence of defect complex formation with ion implanted Mn/Fe in ZnO
/ Mølholt, T E (Iceland U.) ; Mantovan, R (MDM Observ.) ; Gunnlaugsson, H P (Aarhus U.) ; Bharuth-Ram, K (iThemba LABS) ; Fanciulli, M (MDM Observ. ; Milan Bicocca U.) ; Gíslason, H P (Iceland U.) ; Johnston, K (CERN) ; Kobayashi, Y (Wako, RIKEN) ; Langouche, G (Leuven U.) ; Masenda, H (Witwatersrand U.) et al.
57Fe Mössbauer spectroscopy following ion implantation of radioactive 57Mn+ ( T1/2=85.4 s) has been applied to study the formation of Fe/Mn implantation-induced defects in ZnO at temperatures between 319 and 390 K. The formation of ferric iron–vacancy complexes is found to depend strongly on the implanted dose and to be faster and more efficient at higher temperatures [...]
2009
- Published in : Physica B 404 (2009) 4820-4822
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Emission Mössbauer spectroscopy of advanced materials for opto- and nano- electronics
/ Gunnlaugsson, H P (Department of Physics and Astronomy, Aarhus University, DK-8000 Århus C, Denmark) ; Mølholt, T E (Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland) ; Mantovan, R (Laboratorio Nazionale MDM CNR-INFM, 20041 Agrate Brianza (MI), Italy) ; Masenda, H (School of Physics, University of the Witwatersrand, WITS 2050, South Africa) ; Naidoo, D (School of Physics, University of the Witwatersrand, WITS 2050, South Africa) ; Dlamini, W B (University of KwaZulu-Natal, Durban 4001, South Africa) ; Sielemann, R (Helmholtz Forschungszentrum,D-14109 Berlin, Germany) ; Bharuth-Ram, K (iThemba LABS, P.O. Box 722, Somerset West 7129, South Africa) ; Fanciulli, M (Laboratorio Nazionale MDM CNR-INFM, 20041 Agrate Brianza (MI), Italy; Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Milano, Italy) ; Gíslason, H P (Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavík, Iceland) et al.
CERN-INTC-2010-003 ; INTC-P-275.
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2010.
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