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Author(s)
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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.) ; Gislason, Haflidi Petur (Iceland U.) ; Langouche, Guido (Leuven U.) ; Ólafsson, Sveinn (Iceland U.) ; Pereira, Lino M C (Leuven U.) ; Wahl, Ulrich (IST/ITN, Lisbon) ; Torelli, Piero (Trieste, TASC) ; Weyer, Gerd (Aarhus U.) |
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Abstract
| 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. At higher concentrations (between 0.02 and 0.2 at%) a transition to spin–spin type of relaxation between neighboring $Fe^{3+}$ is observed, without any signature of magnetic ordering up to 2.2 at%. Despite the many reports of dilute magnetism in 3 d -doped ZnO, this atomic level study shows no evidence of any long-range magnetic ordering between isolated Fe atoms incorporated in the ZnO lattice. |