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TRANSPORT AND MAGNETIC PROPERTIES OF BI2TE3 SINGLE CRYSTALS DOPED WITH OVERSTICHIOMETRIC TRANSITION METAL

Autoři: Čermák Patrik | Drašar Čestmír | Prokleška Jan | Krejčová Anna | Černohorský Tomáš

Rok: 2016

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

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Jazyk	Název	Abstrakt	Klíčová slova
eng	TRANSPORT AND MAGNETIC PROPERTIES OF BI2TE3 SINGLE CRYSTALS DOPED WITH OVERSTICHIOMETRIC TRANSITION METAL	Recently emerged topological insulators form a new branch of materials with specific surface states, which span ordinary bulk energy gap. These materials are interesting both from the point of basic research and the spintronic applications. Crystals Bi2Se3 and Bi2Te3 receive considerable attention in this field, mainly for their suitable energy band gap and simple Dirac cone. Doping with transient metals could lead to ferromagnetic arrangement in these materials as a result of RKKY interaction (Diluted Magnetic Semiconductor). Thus, doping of these materials by magnetic ions could lead to breaking time-reversal symmetry and opening energy band gap of the surface states. Aim of this work is to contribute to the discussion of doping influence on electric and magnetic properties of Bi2Te3. For this purpose overstoichiometric systems were prepared, for this presentation FexBi2Te3 was selected. Two effects were examined: (1) solubility of Fe in Bi2Te3, where x = 0; 0.02; 0.04; 0.06; 0.08; 0.1, 0.12, 0.14, 0.16 and 0.18 for three weeks annealing below melting point of basic matrix; (2) thermodynamical equilibrium for x = 0,06 without and with annealing for 1 day, 1, 2, 3, 5, 8 and 12 weeks. These materials were characterized by X-ray diffraction, some of them also by SEM EDX, ICP OES and LIBS analysis. Temperature dependence of electric conductivity c, Hall coefficient RH(Bǁc), Seebeck coefficient Tc and magnetic susceptibility (Bǁc, Bc) were measured. Results of magnetic susceptibility show antiferromagnetic arrangement caused presumably by RKKY interaction. Effective magnetic moments per ion calculated from OES results are ~ 2 B. Examined materials are p-type semiconductors to 475 K. By the correlation of electric and magnetic properties we suppose presence of at least two types of Fe ions in octahedral coordination in both types of crystal field. Further research is running.	topological insulators, Bi2Te3 single crystals, doping, transport properties, magnetic properties

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