The (In,Fe)Sb layers with the Fe content up to 13 at. % have been grown on (001) GaAs substrates using the pulsed laser deposition. The TEM investigations show that the (In,Fe)Sb layers are epitaxial and free of the inclusions of a second phase. The observation of the hysteretic magnetoresistance curves at temperatures up to 300 K reveals that the Curie point is above room temperature. The resonant character of magnetic circular dichroism confirms the intrinsic ferromagnetism in the (In,Fe)Sb layers. We suggest that the ferromagnetism of the (In,Fe)Sb matrix is not carrier-mediated and apparently is determined by the mechanism of superexchange interaction between Fe atoms (This work was presented at the XXI Symposium Nanophysics and Nanoelectronics, Nizhny Novgorod, March, 13-16, 2017 (book of proceedings v.1, p. 195), http://nanosymp.ru/UserFiles/Symp/2017_v1.pdf)

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Zinc finger proteins have become one of the most intriguing and interesting targets in biological and medical studies. In recent years some studies have provided new approaches in the manipulation of zinc finger-dependent processes, such as development, tumor, and inflammatory diseases. Paradoxically, those unique properties of this extensive family of proteins depend on metal-binding characteristics, which might be an interesting link between standard approaches to gene therapy and metalloregulation by a numerous intracellular events. This review summarizes some recent achievements in this area of studies. J. Key words: Zn finger proteins; NF-kappa B; Sp1; transition metalsIn the last decade, explosive work in the zinc finger (ZF) field has brought a new understanding of zinc implications in terms of eukaryotic protein-nucleic acid interactions. ZF proteins have become one of the most intriguing and interesting targets in biological and medical studies. However, most of these proteins have never been purified because they are present in exceedingly small quantities in the cell, and, therefore, no direct information on their zinc content is available. Hence, they should be considered only as putative zinc proteins. In recent years, some studies have provided have new approaches in the manipulation of ZF-dependent processes, such as development, tumor, and inflammatory diseases. Paradoxically, these unique properties of this extensive family of proteins depend on metal-binding characteristics, which might represent an interesting connection between standard approaches to gene therapy and metalloregulation of a numerous intracellular events. It is estimated that more than 1% of all mammalian genes encode ZF. Zinc was discovered in more than 300 ZF proteins, including classical ZF in TFIIIA transcription factor from Xenopus laevis, steroid hormone receptors, GATA-1 proteins, LIM domain proteins, RING fingers, and those involved in p53, Sp1, nuclear factor (NF)-B, and Gadd43, PAG608-induced transcription factors [1][2][3]. Members of the homeobox and ZF superfamilies are among the best-characterized transcription factors known to act as potent regulators of normal development in organisms ranging from insects to humans. In addition, mutations or aberrant expression in genes encoding these proteins can result in neoplastic transformation in several different cell types, further support-*Correspondence to: Dr.

The layers of a high-temperature novel GaAs:Fe diluted magnetic semiconductor (DMS) with an average Fe content up to 20 at. % were grown on (001) i-GaAs substrates using a pulsed laser deposition in a vacuum. The transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy investigations revealed that the conductive layers obtained at 180 and 200 ºC are epitaxial, do not contain any second-phase inclusions, but contain the Fe-enriched columnar regions of overlapped microtwins. The TEM investigations of the non-conductive layer obtained at 250 ºC revealed the embedded coherent Fe-rich clusters of GaAs:Fe DMS. The x-ray photoelectron spectroscopy investigations showed that Fe atoms form chemical bonds with Ga and As atoms with almost equal probability and thus the comparable number of Fe atoms substitute on Ga and As sites. The n-type conductivity of the obtained conductive GaAs:Fe layers is apparently associated with electron transport in a Fe acceptor impurity band within the GaAs band gap. A hysteretic negative magnetoresistance (MR) was observed in the conductive layers up to room temperature (RT). MR measurements point to the out-of-plane magnetic anisotropy of the conductive GaAs:Fe layers related to the presence of the columnar regions. The studies of the magnetic circular dichroism confirm that the layers obtained at 180, 200 and 250 ºC are intrinsic ferromagnetic semiconductors and the Curie point can reach up to at least RT in case of the conductive layer obtained at 200 ºC. It was suggested that in heavily Fe-doped GaAs layers the ferromagnetism is related to the Zener double exchange between Fe atoms with different valence states via an intermediate As and Ga atom.

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