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PREPARATION OF NOVEL MAGNETIC SEMICONDUCTORS BASED ON VANADIUM-DOPED Sb2-xBixTe3 CRYSTALS

Rok: 2006

Druh publikace: ostatní - přednáška nebo poster

Název zdroje: Sborník příspěvků 58. SCHS Chemické listy

Název nakladatele: Česká společnost chemická

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Jazyk	Název	Abstrakt	Klíčová slova
cze	PREPARATION OF NOVEL MAGNETIC SEMICONDUCTORS BASED ON VANADIUM-DOPED Sb2-xBixTe3 CRYSTALS	In our previous paper 1, the single crystals of Sb2-xVxTe3 were shown to belong to a new class of materials designated in the literature as diluted magnetic semiconductors (DMS). It was found that a small content of vanadium in the Sb2Te3 crystals gives rise to ferromagnetic behavior at low temperatures; the Curie temperature TC increases with the vanadium content and reaches approximately 23 K for Sb1.97V0.03Te3. A significant feature of this DMS is distinct anisotropy of magnetic properties which is related to the layered structure of tetradymite-type crystals (space group ). It is well known that the Curie temperature depends on carrier concentration for most of DMS. The aim of this paper is to investigate the influence of carrier concentration on TC in vanadium-doped (Sb1-xBix)2Te3. Since the progressive substitution of Sb atoms by Bi atoms in the crystal lattice of Sb2Te3, i.e. creation of solid solutions (Sb1-xBix)2Te3, results in a pronounced decrease in the concentration of holes 2, we have prepared quaternary crystals (Sb1-xBix)2-yVyTe3 with successively increasing x. First, we have prepared polycrystalline materials of composition (Sb1-xBix)1.97V0.03Te3 and (Sb1-xBix)1.98V0.02Te3 for x = 1, 0.75, 0.5, 0.25 and 0 with a view to explore the solubility of vanadium in the solid solutions. X-ray measurements carried out on the samples of (Sb1-xBix)1.97V0.03Te3 for x = 0.5, 0.25 a 0 show diffraction peaks of a minor phase of composition V1.04Te2. However for y = 0.02, there is no evidence of any secondary phase. Therefore, we have focused on single crystals of composition (Sb1-xBix)1.98V0.02Te3. Single crystals were grown by a modified Bridgman method from elements of 5N purity. The samples were characterized by measurements of the temperature dependence of the electrical resistivity, Hall coefficient, and magnetic susceptibility in the temperature range of 2-300 K. In addition, we also measured magneti
eng	PREPARATION OF NOVEL MAGNETIC SEMICONDUCTORS BASED ON VANADIUM-DOPED Sb2-xBixTe3 CRYSTALS	In our previous paper 1, the single crystals of Sb2-xVxTe3 were shown to belong to a new class of materials designated in the literature as diluted magnetic semiconductors (DMS). It was found that a small content of vanadium in the Sb2Te3 crystals gives rise to ferromagnetic behavior at low temperatures; the Curie temperature TC increases with the vanadium content and reaches approximately 23 K for Sb1.97V0.03Te3. A significant feature of this DMS is distinct anisotropy of magnetic properties which is related to the layered structure of tetradymite-type crystals (space group ). It is well known that the Curie temperature depends on carrier concentration for most of DMS. The aim of this paper is to investigate the influence of carrier concentration on TC in vanadium-doped (Sb1-xBix)2Te3. Since the progressive substitution of Sb atoms by Bi atoms in the crystal lattice of Sb2Te3, i.e. creation of solid solutions (Sb1-xBix)2Te3, results in a pronounced decrease in the concentration of holes 2, we have prepared quaternary crystals (Sb1-xBix)2-yVyTe3 with successively increasing x. First, we have prepared polycrystalline materials of composition (Sb1-xBix)1.97V0.03Te3 and (Sb1-xBix)1.98V0.02Te3 for x = 1, 0.75, 0.5, 0.25 and 0 with a view to explore the solubility of vanadium in the solid solutions. X-ray measurements carried out on the samples of (Sb1-xBix)1.97V0.03Te3 for x = 0.5, 0.25 a 0 show diffraction peaks of a minor phase of composition V1.04Te2. However for y = 0.02, there is no evidence of any secondary phase. Therefore, we have focused on single crystals of composition (Sb1-xBix)1.98V0.02Te3. Single crystals were grown by a modified Bridgman method from elements of 5N purity. The samples were characterized by measurements of the temperature dependence of the electrical resistivity, Hall coefficient, and magnetic susceptibility in the temperature range of 2-300 K. In addition, we also measured magneti	diluted magnetic semiconductors Curie temperature

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