The Nature of Magnetic Ordering in Magnetically Doped Topological   Insulator Bi$_{2-x}$Fe$_x$Se$_3$
  We present a detailed investigation of the magnetic and structural properties of magnetically doped 3D topological insulator Bi2Se3. From muon spin relaxation measurements in zero magnetic field, we find that even 5% Fe doping on the Bi site turns the full volume of the sample magnetic at temperatures as high as ~250 K. This is also confirmed by magnetization measurements. Two magnetic "phases" are identified; the first is observed between ~10-250 K while the second appears below ~10 K. These cannot be attributed to impurity phases in the samples. We discuss the nature and details of the observed magnetism and its dependence on doping level. 
Z. Salman, E. Pomjakushina, V. Pomjakushin, A. Kanigel, K. Chashka, K.   Conder, E. Morenzoni, T. Prokscha, K. Sedlak, and A...
cond-mat.str-el cond-mat.mtrl-sci