ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 72
XMCD STUDIES OF THE GaSb:MnSb LAYERS ON THE GaSb AND GaAs SUBSTRATES
A. Wolska1, K. Lawniczak-Jablonska1∗, M.T. Klepka1, and V. Sessi2
1Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL–02668 Warsaw, Poland
2European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble, France Keywords: ferromagnetic precipitates, spintronics, XMCD
∗e-mail : jablo@ifpan.edu.pl
Despite of the intensive search for the proper semiconductor base materials for spintronics no ap- propriate material was proposed so far. In a sin- gle phase material, either ferromagnetism is ob- served below room temperature only [1] or there is no ferromagnetism at all (e.g. GaMnN) [2]. On the other hand, it was demonstrated that during growth of the magnetic III-V semiconductors, pre- cipitates are fairly easily produced, yielding multi- phase ferromagnetic materials (often at room tem- perature) [2]. Recently the increase of interest in producing ferromagnetic precipitates can be ob- served. Among them there are materials consisting of the MnSb nanoinclusions in GaSb semiconduc- tor matrix. It seems that magnetic properties of MnSb are more suitable for spintronic applications, than these of MnAs, since TCof bulk MnSb is much higher — above 300◦C and they are formed only in the hexagonal structure whereas MnAs inclusions usually form both cubic (GaMnAs) and hexagonal inclusions with different magnetic properties [3].
The GaSb:MnSb layers were grown on the GaSb(100) and GaAs(111)A substrates using the MBE technology. The layers on both substrates were grown in the same process in order to investi- gate how the type of a substrate influences the inclu- sions formation. First, the GaSb buffer of 40 – 45 nm was grown and then the GaMnSb layer. The MnSb hexagonal inclusions were formed directly during the epitaxial growth procedure without the post growth annealing. The detailed analysis of the structure of the inclusions by means of the extended X-ray absorption fine structure spectroscopy (EX- AFS) and scanning electron microscopy (SEM) is provided in reference 4, while the magnetic proper- ties are described in reference 5.
The X-ray magnetic circular dichroism (XMCD) experiment was performed at the beamline ID08 (ESRF, Grenoble). X-ray absorption spectra were collected in the total electron yield (TEY) and to- tal fluorescence yield (TFY) modes simultaneously.
The measurements were conducted at temperatures of 3 and 300 K, on the remanently magnetized sam- ples as well as on the samples under the magnetic field of 5 T. The magnetic field used to magnetize samples was oriented along the X-ray path, the an- gle between the surface of the sample and the X-ray beam was being changed from grazing (70◦) to nor- mal (10◦).
The TEY detection mode is sensitive to the near surface region, while the TFY mode is sensitive to the volume of the sample. For the measurements performed under the field, the TFY XMCD signal is considerably stronger than the TEY XMCD one.
Moreover, the TEY XMCD signal shows structure which is not repeated in the TFY signal. In case of the measurements carried out in remanence the TEY XMCD signal cannot be detected.
The investigation on the TFY XMCD signal gathered on the remanently magnetized samples re- vealed that the GaSb:MnSb layers grown on the GaSb(100) and GaAs(111)A substrates exhibit the dichroic signal which shows the angular dependence.
Moreover, this dependence is opposite for both sub- strates.
Acknowledgments: The measurements performed at the ESRF were supported from special project ESRF/73/2006 from the Ministry of Science and High Education. Authors thank Dr. J. Sadowski for provid- ing the samples.
References
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