Univerzita Pardubice Fakulta chemicko- technologická

Univerzita Pardubice

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TRANSPORT AND MAGNETIC PROPERTIES OF FexBi2Te3 SINGLE CRYSTALS

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

Rok: 2016

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	TRANSPORT AND MAGNETIC PROPERTIES OF FexBi2Te3 SINGLE CRYSTALS	Recently emerged topological insulators form a new branch of materials with specific surface states, which span ordinary bulk energy gap. The conductive surface states are produced due to spin-orbital coupling. These states are protected by time-reversal symmetry. 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 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 system FexBi2Te3 was prepared. Two effects was examined: (1) solubility of Fe in Bi2Te3, where x = 0; 0.02; 0.04; 0.06; 0.08; 0.1 and 0.12 for three weeks annealing below melting point of basic matrix; (2) thermodynamical equilibrium for x = 0,06 and annealing for 1 day, 1, 2, 3, 5 and 8 weeks. These materials were characterized by X-ray diffraction, some of them also by SEM EDX and ICP OES 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 shows 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.