Affiliation: | (1) Department of Experimental Physics, Palacky University, Svobody 26, 771 46 Olomouc, Czech Republic;(2) Department of Physics, Belorussian State University, Skoriny Ave 8, Minsk, Belarus;(3) Department of Metallurgy, Technikon Witwatersrand, Doornfontain 2028, Johannesburg, South Africa;(4) Department of Physics, Witwatersrand University, Private Bag 3, Johannesburg, South Africa |