Publications in Scientific Journals:

M. El-Hagary, H. Michor, S. Özcan, M. Giovannini, A. Matar, Z. Heiba, P. Kerschl, M. Schönhart, E. Bauer, R. Grössinger, G. Hilscher, J. Freudenberger, H. Rosner:
"Phase formation and ferrimagnetism of GdCo9Si4";
Journal of Physics: Condensed Matter, 18 (2006), 4567 - 4580.

English abstract:
Phase formation and ferrimagnetism of GdCo9Si4

M El-Hagary et al 2006 J. Phys.: Condens. Matter 18 4567-4580 doi:10.1088/0953-8984/18/19/011

M El-Hagary 1,2, H Michor 1,8, S Özcan 1, M Giovannini 3, A Matar 4, Z Heiba 5, P Kerschl 1, M Schönhart 1, E Bauer 1, R Grössinger 1, G Hilscher 1, J Freudenberger 6 and H Rosner 7

1 Institut für Festkörperphysik, Technische Universität Wien, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
2 College of Science, Physics Department, Qassim University, Buraidah 81999, Kingdom of Saudi Arabia
3 Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, I-16146 Genova, Italy
4 Physics Department, Faculty of Science, Helwan University, Helwan, Cairo, Egypt
5 Physics Department, Faculty of Science, Ain Shams University, Cairo, Egypt
6 Leibniz-Institut für Festköper- und Werkstoffforschung, IFW Dresden, D-01171 Dresden, Germany
7 Max-Planck Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, D-01187 Dresden, Germany
8 Author to whom any correspondence should be addressed
E-mail: michor@ifp.tuwien.ac.at

The phase relations of the GdCo13-xSix system have been studied by means of scanning microscopy, microprobe analysis and x-ray diffraction. Single-phase samples GdCo9+-δ Si4-+δ (structure type LaFe9Si4 with space group I4/mcm) are formed in a narrow composition range |δ| <= 0.2, where GdCo9Si4forms as a fully ordered ternary compound. The magnetic properties of GdCo9Si4 have been investigated by ac susceptibility, magnetization, specific heat and resistivity measurements. These experiments reveal ferrimagnetism below about 47 K, which is analysed in terms of a two-sublattice molecular field model with a local moment Gd subsystem coupling antiparallel to the itinerant ferromagnetic Co 3d sublattice. The 3d-3d exchange of the latter is the driving force for the onset of long range magnetic order. The validity of the two-sublattice model is demonstrated by high field measurements, showing that the ferrimagnetic coupling starts to break up at a lower critical field μ0H1~= 27 T. The magnetic ground state of GdCo9Si4 has been analysed on a microscopic basis via LSDA electronic structure calculations.

Print publication: Issue 19 (17 May 2006)
Received 12 January 2006
Published 26 April 2006

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