IV. Conclusions Fe-doping could keep the lattice of Bi2Se3 unchanged, and the locations of Fe atoms in the Bi2Se3 crystals would change through different growing processes, for which magnetic properties of the whole samples changed. The surface states of Fe0.2Bi1.8Se3 sample were ferromagnetic while the bulk was paramagnetic. Sample preparation and ARPES measurements of Fe-doped Bi2Se3 Zhen Liu, Fuchun Xi, Bin Li and Shan Qiao LAM, Phys. Dept., Fudan Univ., Shanghai, People’s Republic of China Topological insulator is a new state of matter. Bi2Se3 has attracted much attention for its relatively large bulk band gap up to 300 meV in 3D topological insulator class and potential applications on spintronics. Yet, the ferromagnetic properties of magnet doped Bi2Se3 have not been reported. Our attentions are focused on the single crystal growing and ferromagnetic properties of Fe-doped Bi2Se3. I. Sample preparation The element purities were up to %; The single crystals of Fe-doped Bi2Se3 were prepared from pre-synthesized Bi2Se3 and Fe element; The compounds were synthesized in sealed quartz ampoules evacuated to 0.1 Pa; The Fe element and Bi2Se3 should be uniformly mixed before cooling from 800 degree to 550 degree to grow crystals. II. XRD The XRD results of Fe-doped Bi2Se3 are shown below, comparing to the PDF card of Bi2Se3: III. ARPES measurements of Fe0.2Bi1.8Se3 XRD pattern of Fe0.2Bi1.8Se3 PDF card of pure Bi2Se3 The sample was prepared with Bridgeman method, which was paramagnetic tested by SQUID; The experiment temperature was 10K; The red and blue bands, which were derived from the two spectrums respectively, relate to two opposite directions of magnetic field applied on the ferromagnetic sample before detecting the photoelectrons; The magnetic field was in the plane of sample surface and perpendicular to the slit of analyzer.; Both spectrums showed that the surface states were not destroyed by Fe-doping and defects of the crystal; 1. Bridgeman method 2. Solidification in box furnace The element purities were up to %; The single crystals of Fe-doped Bi2Se3 were prepared from pre-synthesized Bi2Se3 and Fe element; The compounds were synthesized in sealed quartz ampoules evacuated to 0.1 Pa; The speed of sample moving was 0.5mm/h; The concentrations of Fe element were decreased after Bridgeman method. XRD pattern of Fe0.05Bi1.95Se3 Fe0.2Bi1.8Se3 was prepared with Bridgeman method while the real factor of Fe was about 0.03 derived from element analysis, which was paramagnetic; Fe0.05Bi1.95Se3 was grown with solidification method in box furnace while the real factor of Fe was about 0.03, which was ferromagnetic; The sameness of the positions of the peaks of the three spectrums implied that the lattice had not been changed by Fe doping; The concentrations of Fe element of the two samples were almost the same while XRD spectrums of them were different, which suggested that the locations of Fe would change through different growing processes. The surface states of Bi2Se3 were spin-polarized which had been reported both theoretically and experimentally; The obviously shift of Dirac point in k-space illustrated ferromagnetic behavior of surface states.