We present the studies of Sn1−xCrxTe semimagnetic semiconductors with chemical composition x ranging from 0.004 to 0.012. The structural characterization indicates that even at low average Cr-content x ≤ 0.012, the aggregation into micrometer size clusters appears in our samples. The magnetic properties are aected by the presence of clusters. In all our samples we observe the transition into the ordered state at temperatures between 130 and 140 K. The analysis of both static and dynamic magnetic susceptibility data indicates that the spin-glass-like state is observed in our samples. The addition of Cr to the alloy seems to shift the spin-glass-like transition from 130 K for x = 0.004 to 140 K for x = 0.012.
2,3,4',6-Tetrachlorobiphenyl (tetraCB) and the corresponding 14C-labelled compound (14C-tetraCB) were synthesized. Two reference compounds, 4-methylthio- and 4-methylsulphonyl-2,3,4',6-tetrachlorobiphenyl were also prepared and characterized. TetraCB and 35S-cysteine were given to groups of female mice. Formation of methyl[35S]sulphonyl-tetraCB was indicated by the presence of extractable sulphuric acid-soluble radioactivity in lung, liver, kidney and fat of the tetraCB-treated mice. As demonstrated by gel permeation chromatography followed by gas chromatography-mass spectrometry, the tissues of the tetraCB-treated mice contained mainly methylsulphonyl-tetraCB, minor amounts of tetraCB and traces of methylthiotetraCB. The major compound present in lung was 4-methylsulphonyl-tetraCB, indicating the presence of specific binding sites for this metabolite in lung tissue. According to autoradiography of mice injected with 14C-tetraCB, these binding sites were present mainly in the tracheo-bronchial mucosa.
The phenomenon of Fano type resonant photoemission was used to distinguish the Fe electrons derived partial contribution to the valence band of a semimagnetic semiconductor Cd1-xFexSe. The states appearing at the middle of the valence band correspond to the Fe 3d electrons while the step of the density of states obtained at the valence band edge region corresponds to the hybridized s p-d electrons. Recently a large amount of effort has been devoted towards under8tanding of the valence band structure of materials with the transition metal ions component, using the resonant photoemission experiment [4][5][6][7]. The photon energy is tuned to the cation 3p -3d optical absorption edge. The state excited in the transition 3p6 3dn -3p5 3dn+ 1 couples with the photoionization continuum 3p 6 3dn-1 + e'
Bulk samples, thin films and quantum dots of II-TM-VI and III-TM-V semiconductor alloys (where TM stands for a transition metal) are intensively studied for their possible spintronics applications. Room temperature ferromagnetism (RT FM) should be achieved in these diluted magnetic semiconductors (DMS) to allow for application of these materials in practical devices. This is an ultimate goal of the investigations.RT FM was theoretically predicted for GaMnN and ZnMnO [1] (and then for other ZnTMO samples), which thus became the most studied spintronics materials. Soon after several groups reported RT FM of ZnMnO and ZnCoO (see e.g. [2]), but this is believed now to be due to inclusions of foreign phases, which we also demonstrate in the present work, and metal accumulations rather than volume properties of these two ZnTMO materials (see e.g. [3,4] and references given there).Origin of the observed magnetic ordering remains often not clear. In the present work we employed scanning electron microscopy (SEM), energy dispersive X-rays spectroscopy (EDS) and cathodoluminescence (CL) methods to investigate topography, uniformity (we also used secondary ions mass spectroscopy (SIMS)) and chemical composition of ZnTMO (TM stands here for Co and Mn) layers grown at low temperature by Atomic Layer Deposition. Samples obtained at these conditions are uniform and show only paramagnetic response, as reported for ZnMnO in [3,4].We demonstrate that these ZnTMO samples show several surprising properties not observed in e.g. ZnTMS. For example, we observed that Mn doping efficiently quenches visible emission of ZnO [5]. We show that this process is still more efficient in ZnCoO, indicating that both Mn and Co ions act as emission deactivators in ZnO. Emission quenching by Mn and Co allows us to study their distribution in ZnO from maps of in-plane changes of the CL intensity. We utilize the fact that the CL intensity anti-correlates with the TM concentration.Strong magneto-optical effects are commonly seen in such DMS samples as CdMnTe. In CdMnTe excitonic emission shifts towards lower energy (by few meV) and splits for photoluminescence measured at different polarizations and magnetic field of a few T [6]. This was observed by us in CdMnTe layers [6] with a similar Mn concentration to the one studied by us at present in ZnMnO. The efect was also reported for p-type ZnMnO layers [7]. Thus, in our magneto-optical investigations of n-type ZnMnO samples we looked for similar effects. Surprisingly, no spectral shifts and well-resolved splitting were observed for magnetic field up to 6 T.
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