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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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2.
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Emission Mössbauer spectroscopy study of fluence dependence of paramagnetic relaxation in Mn/Fe implanted ZnO
/ Masenda, H (Witwatersrand U.) ; Geburt, S (Institute of Solid State PhysicsUniversity of JenaJenaGermany ; Jena U.) ; Bharuth-Ram, K (DUT, Durban ; KwaZulu Natal U.) ; Naidoo, D (Witwatersrand U.) ; Gunnlaugsson, H P (CERN ; Leuven U.) ; Johnston, K (CERN) ; Mantovan, R (IMM-CNR, Brianza) ; Mølholt, T E (CERN) ; Ncube, M (Witwatersrand U.) ; Shayestehaminzadeh, S (RWTH Aachen U.) et al.
/ISOLDE
Emission Mössbauer Spectroscopy following the implantation of radioactive precursor isotope $^{57}$Mn$^{+}$ (T$_{1/2}$= 1.5 min) into ZnO single crystals at ISOLDE/CERN shows that a large fraction of $^{57}$Fe atoms produced in the $^{57}$Mn beta decay is created as paramagnetic Fe$^{3+}$ with relatively long spin-lattice relaxation times. Here we report on ZnO pre-implanted with $^{56}$Fe to fluences of 2×10$^{13}$, 5×10$^{13}$ and 8 × 10$^{13}$ ions/cm2 in order to investigate the dependence of the paramagnetic relaxation rate of Fe$^{3+}$ on fluence. [...]
2016 - 7 p.
- Published in : Hyperfine Interact. 237 (2016) 40
Fulltext: PDF; External link: Link to fulltext on ICAME2015 document server
In : International Conference on the Applications of the Mössbauer Effect, Hamburg, Germany, 13 - 18 Sep 2015, pp.40
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3.
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Charge states and lattice sites of dilute implanted Sn in ZnO
/ Mølholt, T E (CERN) ; Gunnlaugsson, H P (Leuven U.) ; Johnston, K (CERN) ; Mantovan, R (CNR-IMM Agrate Brianza, Italy) ; Röder, J (CERN ; RWTH Aachen U.) ; Adoons, V (KwaZulu Natal U.) ; Mokhles Gerami, A (CERN ; K.N. Toosi U.) ; Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Matveyev, Y A (Moscow, MIPT) ; Ncube, M (U. Witwatersrand, Johannesburg, Sch. Phys.) et al.
/ISOLDE
The common charge states of Sn are 2+ and 4+. While charge neutrality considerations favour 2+ to be the natural charge state of Sn in ZnO, there are several reports suggesting the 4+ state instead. [...]
2017
- Published in : J. Phys. : Condens. Matter 29 (2017) 155701
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4.
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Sensitivity of $^{57}$Fe emission Mössbauer spectroscopy to Ar and C induced defects in ZnO
/ Bharuth-Ram, K (DUT, Durban) ; Mølholt, T E (CERN) ; Langouche, G (Leuven U.) ; Geburt, S (U. Jena (main)) ; Ronning, C (U. Jena (main)) ; Doyle, T B (iThemba LABS ; KwaZulu Natal U.) ; Gunnlaugsson, H P (CERN) ; Johnston, K (CERN) ; Mantovan, R (IMM-CNR, Brianza) ; Masenda, H (Witwatersrand U.) et al.
/Isolde
Emission Mössbauer Spectroscopy (eMS) measurements, following low fluence (<1012 cm−2) implantation of 57Mn (t 1/2 = 1.5 min.) into ZnO single crystals pre-implanted with Ar and C ions, has been utilized to test the sensitivity of the 57Fe eMS technique to the different types of defects generated by the different ion species. The dominant feature of the Mössbauer spectrum of the Ar implanted ZnO sample was a magnetic hyperfine field distribution component, attributed to paramagnetic Fe3+, while that of the C implanted sample was a doublet attributed to substitutional Fe2+ forming a complex with the C dopant ions in the 2− state at O vacancies. [...]
2016
- Published in : Hyperfine Interact. 237 (2016) 81
External link: Link to fulltext on ICAME2015 document server
In : International Conference on the Applications of the Mössbauer Effect, Hamburg, Germany, 13 - 18 Sep 2015, pp.81
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5.
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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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6.
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Lattice sites, charge states and spin–lattice relaxation of Fe ions in 57Mn+ implanted GaN and AlN
/ Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Naidoo, D (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Bharuth-Ram, K (DUT, Durban ; iThemba LABS) ; Gunnlaugsson, H P (CERN ; KU Leuven, Dept. Phys. Astron.) ; Johnston, K (CERN) ; Mantovan, R (CNR-IMM Agrate Brianza, Italy) ; Mølholt, T E (CERN) ; Ncube, M (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Shayestehaminzadeh, S (RWTH Aachen U.) ; Gíslason, H P (Iceland U.) et al.
The lattice sites, valence states, resulting magnetic behaviour and spin–lattice relaxation of Fe ions in GaN and AlN were investigated by emission Mössbauer spectroscopy following the implantation of radioactive $^{57}Mn^+$ ions at ISOLDE/CERN. Angle dependent measurements performed at room temperature on the 14.4 keV γ-rays from the 57Fe Mössbauer state (populated from the $^{57}$Mn $β ^−$ decay) reveal that the majority of the Fe ions are in the 2+ valence state nearly substituting the Ga and Al cations, and/or associated with vacancy type defects. [...]
2016 - 9 p.
- Published in : J. Magn. Magn. Mater. 401 (2016) 1130-1138
Fulltext: PDF;
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7.
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$^{57}$ Fe Emission Mössbauer Study on $Gd_3 Ga_5 O_{12}$ implanted with dilute $^{57} Mn$
/ Krastev, P B (Sofiya, Inst. Nucl. Res.) ; Gunnlaugsson, H P (CERN) ; Nomura, K (Tokyo U. of Sci.) ; Adoons, V (Zululand U.) ; Gerami, A M (CERN ; K.N. Toosi U.) ; Johnston, K (CERN) ; Ncube, M (Witwatersrand U.) ; Mantovan, R (IMM-CNR, Brianza) ; Masenda, H (Witwatersrand U.) ; Matveyev, Y A (Moscow, MIPT) et al.
/ISOLDE
$^57$Fe emission Mössbauer spectroscopy has been applied to study the lattice location and properties of Fe in gadolinium gallium garnet $Gd_3 Ga_5 O_{12}$ (GGG) single crystals in the temperature interval 300 – 563 K within the extremely dilute (<10$^{−4}$ at.%) regime following the implantation of$^{57}$Mn (T$_{1 / 2}$= 1.5 min.) at ISOLDE/CERN. These results are compared with earlier Mössbauer spectroscopy study of Fe-doped gadolinium gallium garnet $Gd_3 Ga_5 O_{12}$(GGG), with implantation fluences between 8×10$^{15}$ and 6×10$^{16}$ atoms cm $^{−2}$. [...]
2016 - 6 p.
- Published in : Hyperfine Interact. 237 (2016) 37
External link: Link to fulltext on ICAME2015 document server
In : International Conference on the Applications of the Mössbauer Effect, Hamburg, Germany, 13 - 18 Sep 2015, pp.37
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8.
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Defect annealing in Mn/Fe-implanted TiO2(rutile)
/ Gunnlaugsson, H P (Aarhus U.) ; Mantovan, R (IMM, Bologna) ; Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Mølholt, T E (Iceland U.) ; Johnston, K (CERN) ; Bharuth-Ram, K (Durban-Westville U.) ; Gislason, H (Iceland U.) ; Langouche, G (Leuven U.) ; Naidoo, D (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Ólafsson, S (Iceland U.) et al.
A study of the annealing processes and charge state of dilute Fe in rutile TiO2 single crystals was performed in the temperature range 143-662 K, utilizing online 57Fe emission Mossbauer spectroscopy following low concentrations (< 10(-3) at\%) implantation of 57Mn (T-1/2 = 1.5 min). Both Fe3+ and Fe2+ were detected throughout the temperature range. [...]
2014
- Published in : J. Phys. D 47 (2014) 065501
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9.
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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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10.
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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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