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Unusual charge states and lattice sites of Fe in Al$_{x}$Ga$_{1−x}$N:Mn
/ Masenda, Hilary (Witwatersrand U. ; Philipps U. Marburg) ; Gunnlaugsson, Haraldur Páll (Iceland U.) ; Adhikari, Rajdeep (Linz U.) ; Bharuth-Ram, Krish (DUT, Durban) ; Naidoo, Deena (Witwatersrand U.) ; Tarazaga Martín-Luengo, Aitana (Linz U.) ; Unzueta, Iraultza (Basque U., Bilbao) ; Mantovan, Roberto (CNR-IMM, Catania) ; Mølholt, Torben Esmann (CERN) ; Johnston, Karl (CERN) et al.
Charge states and lattice sites of Fe ions in virgin and Mn-doped Al$_{x}$Ga$_{1−x}$N samples were investigated using $^{57}$Fe emission Mössbauer spectroscopy following radioactive $^{57}$Mn$^{+}$ ion implantation at ISOLDE, CERN. In the undoped Al$_{x}$Ga$_{1−x}$N, Fe$^{2+}$ on Al/Ga sites associated with nitrogen vacancies and Fe$^{3+}$ on substitutional Al/Ga sites are identified. [...]
2022 - 12 p.
- Published in : New J. Phys. 24 (2022) 103007
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Temperature Dependence of the Hyperfine Magnetic Field at Fe Sites in Ba-Doped BiFeO$_3$ Thin Films Studied by Emission Mössbauer Spectroscopy
/ Heiniger-Schell, Juliana (CERN ; Duisburg-Essen U.) ; Bharuth-Ram, Krish (ENS, Lyon, Lab. Phys. ; KwaZulu Natal U. ; DUT, Durban) ; Naicker, Kimara (ENS, Lyon, Lab. Phys. ; KwaZulu Natal U.) ; Masondo, Vusumuzi (DUT, Durban) ; Dang, Thien Thanh (Duisburg-Essen U.) ; Escobar, Marianela (Duisburg-Essen U.) ; Díaz-Guerra, Carlos (Madrid U.) ; Marschick, Georg (Vienna, Tech. U.) ; Masenda, Hilary (Witwatersrand U.) ; Gunnlaugsson, Haraldur P (Iceland U.) et al.
Emission $^{57}$Fe Mössbauer spectroscopy (eMS), following the implantation of radioactive $^{57}$Mn+ ions, has been used to study the temperature dependence of the hyperfine magnetic field at Fe sites in Ba-doped BiFeO$_3$ (BFO) thin films. $^{57}$Mn β decays (t$_{1/2}$ = 90 s) to the 14.4 keV Mössbauer state of $^{57}$Fe, thus allowing online eMS measurements at a selection of sample temperatures during Mn implantation. [...]
2023 - 13 p.
- Published in : Crystals 13 (2023) 724
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Anisotropy of the Electric Field Gradient in Two-Dimensional α-MoO$_3$ Investigated by $^{57}$Mn($^{57}$Fe) Emission Mössbauer Spectroscopy
/ Schell, Juliana (CERN ; Duisburg-Essen U.) ; Zyabkin, Dmitry (Ilmenau Tech. U.) ; Bharuth-Ram, Krish (KwaZulu Natal U.) ; Gonçalves, João N (Aveiro U.) ; Díaz-Guerra, Carlos (Madrid U.) ; Gunnlaugsson, Haraldur P (Iceland U.) ; Martín-Luengo, Aitana Tarazaga (Linz U.) ; Schaaf, Peter (Ilmenau Tech. U.) ; Bonanni, Alberta (Linz U.) ; Masenda, Hilary (Witwatersrand U. ; Philipps U. Marburg) et al.
Van der Waals α-MoO3 samples offer a wide range of attractive catalytic, electronic, and optical properties. We present herein an emission Mössbauer spectroscopy (eMS) study of the electric-field gradient (EFG) anisotropy in crystalline free-standing α-MoO3 samples. [...]
2022 - 13 p.
- Published in : Crystals 12 (2022) 942
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Local increase of the Curie temperature in Mn/Fe implanted Y$_{3}$Fe$_{5}$O$_{12}$ (YIG)
/ Krastev, P B (Sofiya, Inst. Nucl. Res.) ; Gunnlaugsson, H P (Iceland U.) ; Nomura, K (Tokyo Metropolitan U.) ; Bharuth-Ram, K (DUT, Durban ; KwaZulu Natal U.) ; Qi, B (Iceland U.) ; Masenda, H (Witwatersrand U.) ; Mølholt, T E (Roskilde U., IMFUFA ; CERN) ; Naidoo, D (Witwatersrand U.) ; Ólafsson, S (Iceland U.) ; Tarazaga Martín-Luengo, A (Linz U.) et al.
The change in the Curie temperature of single crystalline garnet Y$_{3}$Fe$_{5}$O$_{12}$ (YIG) sample due to lattice damage induced by ion implantation has been investigated in $^{57}$Fe emission Mössbauer Spectroscopy (eMS) following implantation of $^{57}$Mn (T½=1.5 min). The Mössbauer spectra analysis reveal high spin Fe $^{3+}$ ions substituted on both the octahedral and the tetrahedral sites. [...]
2020
- Published in : Appl. Radiat. Isot. 160 (2020) 109121
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Multiferroic bismuth ferrite: Perturbed angular correlation studies on its ferroic $\alpha$-$\beta$ phase transition
/ Marschick, G (Vienna, Tech. U. ; CERN) ; Schell, J (CERN ; U. Duisburg-Essen) ; Stöger, B (Vienna, Tech. U.) ; Gonçalves, J N (Aveiro U.) ; Karabasov, M O (U. Duisburg-Essen) ; Zyabkin, D (Ilmenau Tech. U.) ; Welker, A (CERN) ; Escobar C , M (U. Duisburg-Essen) ; Gärtner, D (Munster U.) ; Efe, I (Zurich, ETH) et al.
Work of numerous research groups has shown different outcomes of studies of the transition from the ferroelectric $\alpha$-phase to the high temperature $\beta$-phase of the multiferroic, magnetoelectric perovskite Bismuth Ferrite (BiFeO$_{3}$ or BFO). Using the perturbed angular correlation (PAC) method with $^{111m}$Cd as the probe nucleus, the $\alpha$ to $\beta$ phase transition was characterized. [...]
2020 - 11 p.
- Published in : Phys. Rev. B 102 (2020) 224110
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Temperature dependence of the local electromagnetic field at the Fe site in multiferroic bismuth ferrite
/ Dang, T T (U. Duisburg-Essen) ; Schell, J (U. Duisburg-Essen ; CERN) ; Boa, A G (Denmark, Tech. U.) ; Lewin, D (U. Duisburg-Essen) ; Marschick, G (TU Vienna) ; Dubey, A (U. Duisburg-Essen) ; Escobar-Castillo, M (Duisburg-Essen U.) ; Noll, C (Bonn U., HISKP) ; Beck, R (Bonn U., HISKP) ; Zyabkin, Dmitry V (Ilmenau Tech. U.) et al.
In this paper, we present a study of the temperature-dependent characteristics of electromagnetic fields at the atomic scale in multiferroic bismuth ferrite (BiFeO$_3$ or BFO). The study was performed using time differential perturbed angular correlation (TDPAC) spectroscopy on implanted 111In (111Cd) probes over a wide temperature range. [...]
2022 - 15 p.
- Published in : Phys. Rev. B 106 (2022) 054416
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Charge and spin state of dilute Fe in NaCl and LiF
/ ISOLDE Collaboration
There is an apparent mismatch between electron paramagnetic resonance and Mössbauer spectroscopy results on the charge and spin states of dilute Fe impurities in NaCl; Mössbauer spectroscopy data have been interpreted in terms of high-spin Fe$^{2+}$, while electron paramagnetic resonance studies suggest low-spin Fe$^{1+}$. In the present study, the charge and spin states of dilute substitutional Fe impurities in NaCl and LiF have been investigated with $^{57}$Mn → $^{57}$Fe emission Mössbauer spectroscopy. [...]
2022 - 10 p.
- Published in : Phys. Rev. B 106 (2022) 174108
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Experimental and Theoretical Study of Electronic and Hyperfine Properties of Hydrogenated Anatase (TiO2): Defect Interplay and Thermal Stability
/ Zyabkin, D V (Palacky U. ; Ilmenau Tech. U.) ; Gunnlaugsson, H P (Iceland U.) ; Gonçalves, J N (Aveiro U.) ; Bharuth-Ram, K (KwaZulu Natal U. ; DUT, Durban) ; Qi, B (Iceland U.) ; Unzueta, I (Basque U., Bilbao) ; Naidoo, D (Witwatersrand U.) ; Mantovan, R (CNR-IMM, Catania) ; Masenda, H (Witwatersrand U.) ; Ólafsson, S (Iceland U.) et al.
The performance of TiO$_2$-based materials is highly dependent on the electronic structure and local defect configurations. Hence, a thorough understanding of defect interaction plays a key role. [...]
2020 - 12 p.
- Published in : The Journal of Physical Chemistry C 124 (2020) 7511-7522
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Annealing studies combined with low temperature emission Mössbauer spectroscopy of short-lived parent isotopes: Determination of local Debye–Waller factors
/ Gunnlaugsson, H P (Iceland U.) ; Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Mølholt, T E (Denmark, Tech. U.) ; Bharuth-Ram, K (KwaZulu Natal U. ; DUT, Durban) ; Ólafsson, S (Iceland U.) ; Johnston, K (CERN) ; Schell, J (CERN ; Duisburg-Essen U.) ; Gislason, H P (Iceland U.) ; Krastev, P B (Sofiya, Inst. Nucl. Res.) ; Mantovan, R (SGS Thomson, Milan) et al.
An extension of the online implantation chamber used for emission Mössbauer Spectroscopy (eMS) at ISOLDE/CERN that allows for quick removal of samples for offline low temperature studies is briefly described. We demonstrate how online eMS data obtained during implantation at temperatures between 300 K and 650 K of short-lived parent isotopes combined with rapid cooling and offline eMS measurements during the decay of the parent isotope can give detailed information on the binding properties of the Mössbauer probe in the lattice. [...]
2021
- Published in : Rev. Sci. Instrum. 92 (2021) 013901
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