Development of Ferromagnetism in the Doped Topological Insulator Bi2-x MnxTe3
The development of ferromagnetism in Mn-doped Bi2Te3 is characterized through measurements on a series of single crystals with different Mn content. Scanning tunneling microscopy analysis shows that the Mn substitutes on the Bi sites, forming compounds of the type Bi2-xMnxTe3, and that the Mn substitutions are randomly distributed, not clustered. Mn doping first gives rise to local magnetic moments with Curie-like behavior, but by the compositions Bi1.96 Mn0.04 Te3 and Bi1.91 Mn0.09 Te3, a second-order ferromagnetic transition is observed, with TC ~9-12 K. The easy axis of magnetization in the ferromagnetic phase is perpendicular to the Bi2 Te3 basal plane. Thermoelectric power and Hall effect measurements show that the Mn-doped Bi2Te3 crystals are p -type. Angle-resolved photoemission spectroscopy measurements show that the topological surface states that are present in pristine Bi2 Te3 are also present at 15 K in ferromagnetic Mn-doped Bi2-x MnxTe3 and that the dispersion relations of the surface states are changed in a subtle fashion.
Y. S. Hor and P. Roushan and H. Beidenkopf and J. Seo and D. Qu and J. G. Checkelsky and L. A. Wray and D. Hsieh and Y. Xia and S. Xu and D. Qian and M. Z. Hasan and N. Ong and A. M. Yazdani and R. J. Cava, "Development of Ferromagnetism in the Doped Topological Insulator Bi2-x MnxTe3," Physical Review B - Condensed Matter and Materials Physics, vol. 81, no. 19, American Physical Society (APS), May 2010.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevB.81.195203
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