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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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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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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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4.
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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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Metal-insulator transition in crystalline V$_2$O$_3$ thin films probed at atomic-scale using emission Mössbauer spectroscopy
/ Qi, B (Iceland U.) ; Gunnlaugsson, H P (Iceland U.) ; Ólafsson, S (Iceland U.) ; Gislason, H P (Iceland U.) ; Thorsteinsson, E B (Iceland U.) ; Arnalds, U B (Iceland U.) ; Mantovan, R (CNR-IMM, Catania) ; Unzueta l, I (Basque U., Bilbao) ; Zyabkin, D V (Ilmenau Tech. U.) ; Bharuth Ram, K (KwaZulu Natal U. ; DUT, Durban) et al.
Microscopic understanding the metal-to-insulator transition (MIT) in strongly correlated materials is critical to
the design and control of modern “beyond silicon” Mott nanodevices. In this work, the local MIT behaviors in
single crystalline V$_2$O$_3$ thin films were probed on an atomic scale by online $^{57}$Fe emission Mössbauer spectroscopy (eMS) following dilute ($<10^{-3}$ at.%) implantation of $^{57}$Mn$^+$ (T$_{1/2}$ = 90 s). [...]
2020
- Published in : Thin Solid Films 714 (2020) 138389
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6.
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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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$^{57}$Fe Mössbauer study of epitaxial TiN thin film grown on MgO (1 0 0) by magnetron sputtering
/ Qi, B (Iceland U.) ; Gunnlaugsson, H P (Iceland U.) ; Mokhles Gerami, A (K.N. Toosi U.) ; Gislason, H P (Iceland U.) ; Ólafsson, S (Iceland U.) ; Magnus, F (Iceland U.) ; Mølholt, T E (CERN) ; Masenda, H (U. Witwatersrand, Johannesburg, Sch. Phys.) ; Tarazaga Martín-Lueugo, A (Linz U.) ; Bonanni, A (Linz U.) et al.
/ISOLDE
The properties and performance of TiN thin films are closely related to the concentration and mobility of lattice defects in the thin film structures of TiN. This makes a local atomic scale study of TiN thin films an ever-growing demand. [...]
2019 - 10 p.
- Published in : Appl. Surf. Sci. 464 (2019) 682-691
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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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Cd implantation in α-MoO3: An atomic scale study
/ Gerami, Adeleh Mokhles (IPM, Tehran ; CERN) ; Heiniger-Schell, Juliana (CERN ; Duisburg-Essen U.) ; da Silva, E Lora (Porto U.) ; Costa, Messias S (Para U.) ; Costa, Cleidilane S (Para U.) ; Monteiro, João G (IST/ITN, Lisbon) ; Pires, José J (Lisbon, CFTP) ; Pereira, Daniela R (Lisbon, ISEL) ; Díaz-Guerra, Carlos (Madrid U.) ; Carbonari, Artur W (IPEN, Sao Paulo) et al.
Lamellar α-MoO3 crystals were implanted with low fluence of radioactive Cd111m ions at ISOLDE-CERN. Subsequently, we have probed the interaction of the Cd impurity in the lattice with native point defects, such as oxygen vacancies, as a function of annealing temperature using the time differential perturbed angular correlations nanoscopic technique. [...]
2023 - 15 p.
- Published in : Phys. Rev. Mater. 7 (2023) 033603
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Strong magnetoelectric coupling at an atomic nonmagnetic electromagnetic probe in bismuth ferrite
/ Schell, Juliana (CERN ; Duisburg-Essen U.) ; Schmuck, Merlin (Duisburg-Essen U.) ; Efe, İpek (Zurich, ETH) ; Dang, Thien Thanh (Duisburg-Essen U.) ; Gonçalves, João Nuno (Aveiro U.) ; Lewin, Daniil (Duisburg-Essen U.) ; Castillo, Marianela Escobar (Duisburg-Essen U.) ; Shvartsman, Vladimir V (Duisburg-Essen U.) ; Costa, Ângelo Rafael Granadeiro (CERN ; Lisbon, IST) ; Köster, Ulli (Laue-Langevin Inst.) et al.
Isolated nonmagnetic substitutional defect ions experience huge coupled electric magnetic interaction in the single-phase multiferroic BiFeO$_{3}$. In the ferroelectric state above the magnetic Néel temperature $T$$_{N}$, the electric environment generates a single symmetric electric field gradient (EFG) parallel to the electric polarization direction. [...]
2022 - 13 p.
- Published in : Phys. Rev. B 105 (2022) 094102
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