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Superconductivity by Sr Intercalation in Layered Topological Insulator Bi2Se3

Strontium intercalation between van der Waals bonded layers of topological insulator Bi2Se3 is found to induce superconductivity with a maximum Tc of 2.9 K. Transport measurement on single crystal of optimally doped sample Sr0.1Bi2Se3 shows weak anisotropy (1.5) and upper critical field Hc2(0) equals to 2.1 T for magnetic field applied per-pendicular to c -axis of the sample. The Ginzburg-Landau coherence lengths are Xi-ab = 15.3 Å and Xi_c = 10.2 Å. The lower critical field and zero temperature penetration depth Lambda(0) are estimated to be 0.35 mT and 1550 nm respectively. Hall and Seebeck measurements confirm the dominance of electronic conduction and the carrier concentration is surprisingly low (n = 1.85 x 10^19 cm-3) at 10 K indicating possibility of unconventional superconductivity.