4-8 July 2016
Kramer Law building
Africa/Johannesburg timezone
<a href="http://events.saip.org.za/internalPage.py?pageId=10&confId=86">The Proceedings of SAIP2016</a> published on 24 December 2017

Search for dilute magnetism in 3<i>d</i> doped III-Nitrides - Results from Mössbauer Spectroscopy

8 Jul 2016, 15:20
20m
LT1 (Kramer Law building)

LT1

Kramer Law building

UCT Middle Campus Cape Town
Oral Presentation Track A - Division for Physics of Condensed Matter and Materials Division for Physics of Condensed Matter and Materials (1)

Speaker

Dr Hilary Masenda (School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa)

Abstract content <br> &nbsp; (Max 300 words)<br><a href="http://events.saip.org.za/getFile.py/access?resId=0&materialId=0&confId=34" target="_blank">Formatting &<br>Special chars</a>

ZnO and GaN doped with transitions metals have attracted much attention since the theoretical prediction[1] that wide band-gap materials are potential dilute magnetic semiconductors with high Curie temperatures (Tc ≥ 300 K), resulting from carrier mediated magnetic interactions due to itinerant holes coupling with localized dopant spins. This motivated our investigations on the site occupancy and magnetic behaviour of Fe ions in III-nitrides using emission Mössbauer spectroscopy (eMS) following the implantation of radioactive 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 57Mn β- decay) reveal that the majority of the Fe ions are in the 2+ valence state located near substitutional and/or associated with vacancy type defects. eMS experiments conducted over a temperature range of 100-800 K show the presence of magnetically-split sextets in the “wings” of the spectra for GaN and AlN, as observed in ZnO[2]. The temperature dependence of the sextets relate these spectral features to paramagnetic Fe3+ (S=5/2) with rather slow spin-lattice relaxation rates which follow a T2 temperature dependence characteristic of a two-phonon Raman process. However, InN did not show the presence of any magnetic structure in the spectra suggesting the absence of high spin Fe3+ in the material. These results will be compared to those obtained in 3d-doped ZnO[3].

[1] Dietl, T. et al: Science, 287 (2000) 1019.


[2] Gunnlaugsson, H. P., et al: Appl. Phys. Lett., 97 (2010) 142501.


[3] Mølholt, T. E. et al: Phys. Scr., T148 (2012) 014006.

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Primary author

Dr Hilary Masenda (School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa)

Co-authors

Prof. Deena Naidoo (School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa) Prof. Gerd Weyer (Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus, Denmark) Prof. Guido Langouche (Instituut voor Kern- en Stralings fysika, University of Leuven (KU Leuven), Belgium) Prof. Hafliði Pétur Gíslason (Science Institute, University of Iceland, Dunhaga 3,107 Reykjavík, Iceland,) Prof. Haraldur Pall Gunnlaugsson (PH Dept, ISOLDE/CERN, 1211 Geneva 23, Switzerland) Dr Karl Johnston (PH Dept, ISOLDE/CERN, 1211 Geneva 23, Switzerland) Prof. Krish Bharuth-Ram (School of Physics, Durban University of Technology, Durban 4000, South Africa) Mr Mehluli Ncube (School of Physics, University of the Witwatersrand, Johannesburg, 2050, South Africa) Dr Roberto Mantovan (Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864 Agrate Brianza (MB), Italy) Dr Seyedmohammad Shayestehaminzade (Institute of Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 52074 Aachen, Germany) Prof. Sveinn Ólafsson (Science Institute, University of Iceland, Dunhaga 3,107 Reykjavík, Iceland) Dr Torben Esmann Mølholt (PH Dept, ISOLDE/CERN, 1211 Geneva 23, Switzerland)

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