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MAGNETIC SYSTEMS 2009Anomalous Hall effect in (Ge,Mn)Te-(Sn,Mn)Te spin-glasslike crystalsThe anomalous Hall effect shows a direct interplay betweenmagnetic and electronic properties of solid. Inthis contribution, we show the results of the anomalousHall effect studies in the series of Ge 1-x-y Sn x Mn y Tecrystals with chemical composition 0.090≤x≤0.142 and0.012≤y≤0.115 in the temperature range 1.4≤T ≤200 Kand magnetic fields up to 130 kOe. Recent investigation ofmagnetic properties of this alloy [Kilanski, et al., J. Appl.Phys. 105, 103901 (2009)] showed the presence of the spinglasslikestate with transition temperatures T SG ≤60 K.R S is probably more complex function of both magneticand electrical properties than just chemical compositionof the alloy. It may be noted that the obtained anomalousHall constants are similar to the ones observed in the literaturefor other IV-VI based diluted magnetic semiconductorslike Sn 1-x Mn x Te and Ge 1-x-y Mn x Eu y Te [Brodowska, et al.,Journal of Alloys and Compounds. 423, 205 (2006)].The magnetic field dependence of the resistivity tensorcomponent ρ xy for Ge 0.815 Sn 0.091 Mn 0.094 Te crystal at temperaturerange 4.3≤T ≤50 K is presented in figure 107. Thesharp increase of ρ xy (B) dependence visible in the low fieldregion is the manifestation of the anomalous Hall effect (attemperatures lower than T SG ). The off-diagonal resistivityρ xy (B) is a sum of ordinary R H and anomalous R S contributiondescribed by the following equationρ xy = R H B + µ 0 R S M(H), (15)where µ 0 is a magnetic permeability of vacuum. In orderto determine the anomalous Hall constant the isothermalmagnetization curves M(H) were measured at thesame temperatures in which magnetotransport effectswere investigated. The magnetization curves for selectedGe 0.850 Sn 0.119 Mn 0.031 Te crystal are presented in figure 108.The M(H) dependencies (see figure 108) shows nonsaturatingbehavior even at magnetic fields as high as 100 kOe.The magnetization curves observed at temperatures lowerthan spin-glass freezing temperature showed behavior differentthan that for spin-glass system, namely the largespontaneous magnetization. The experimental M(H)curves are more complex than that of a Weiss ferromagnetwhat may be interpreted that short range interactionsplay an important role in this system. The maximum valuesof magnetization obtained in each crystal were slightlysmaller than the estimated using chemical composition ofthe alloy. It indicates, that possibly a fraction of Mn ionsremained in a spin state reducing their magnetic moment orthere exists antiferromagnetic clusters.The equation 1 was fitted to the experimental data in orderto extract values of ordinary R H and anomalous R SHall coefficients. The obtained values of R S varies betweencrystals with a different amount of both alloyingelements by about an order of magnitude in the range of2.7×10 −5 cm 3 /C and 30×10 −5 cm 3 /C. The chemical compositionof the alloy has significant effect on the R S i.e. itdecreases with the amount of Sn in the alloy and increasewith the Mn content. It must be noted, however that theFigure 107: Magnetic field dependence of the off-diagonal resistivityρ xy obtained for selected Ge 0.815 Sn 0.091 Mn 0.094 Te crystal.Figure 108: Magnetetization curves obtained at different temperatures(see legend) for selected Ge 0.850 Sn 0.119 Mn 0.031 Te crystal.A. B. AntunesL. Kilanski, W. Dobrowolski (Institute of Physics Polish Academy of Science, Warsaw, Poland), V. E. Slynko, E. I.Slynko (Institute of Materials Science Problems, Ukrainian Academy of Sciences, Chernovtsy, Ukraine)80