Antiferromagnetic order competing with topological state in CexBi2-xTe3

초록

The topological surface states in three-dimensional topological insulators are easily tuned by chemical doping, especially by magnetic impurities. We prepared single crystals of CexBi2-xTe3 with various x (=0.04, 0.06, 0.08, 0.10, and 0.12). The obtained crystals were characterized by X-ray diffraction and scanning electron microscopy. The magnetic susceptibility data revealed that the Ce atoms are well substituted for Bi into Bi2Te3. From the Curie-Weiss fits, we observed that the effective magnetic moments mu(eff) are close to 2.54 mu B for free Ce ion, and the paramagnetic Curie-Weiss temperatures theta(p) are negatively increased from 2.87 K to -59.3 K with increasing x. The magnetization data clearly showed antiferromagnetic orders around T-N = 4.1 K for x >= 0.08, where theta(p) suddenly increases, and the electrical resistivity is simply metallic and the magnetoresistance is parabolic. Only for x = 0.06, exotic physical properties arising from the topological states were observed such as non-metallic behavior in the electrical resistivity and linear dependence of the magnetoresistance. Moreover, the carrier concentration of x = 0.06 is one order lower than that of x >= 0.08. These observations propose that the antiferromagnetic order is strongly competing with the topological state in CexBi(2-x)Te(3). (C) 2015 AIP Publishing LLC.

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