Unusual non saturating Giant Magneto-resistance in single crystalline Bi2Te3 topological insulator

We report synthesis, structural details and electrical transport properties of topological insulator Bi2Te3. The single crystalline specimens of Bi2Te3 are obtained from high temperature (950 °C) melt and slow cooling (2 °C/hour). The resultant crystals were shiny, one piece (few cm) and of bright silver color. The Bi2Te3 crystal is found to be perfect with clear [00l] alignment. The powder XRD pattern being carried out on crushed crystals showed that Bi2Te3 crystallized in R3̅m symmetry with a=b=4.3866(2) Å, c=30.4978(13) Å and γ=120°. The Bi position is refined to (0, 0, 0.4038 (9)) at Wyckoff position 6c and of Te are (0, 0, 0) at Wyckoff position 3a and at (0, 0, 0.2039(8)) at 6c. Ambient pressure and low temperature (down to 2 K) electrical transport measurements revealed metallic behavior. Magneto transport measurements under magnetic field showed huge non saturating magneto resistance (MR) reaching up to 250% at 2.5 K and under 50 kOe field. Summarily, the short communication clearly demonstrates that Bi2Te3 topological insulator exhibit non-saturating large positive MR at low temperature of say below 10 K. The non saturating MR is seen right up to room temperature albeit with much decreased magnitude. Worth mentioning is the fact that these crystals are bulk in nature and hence the anomalous MR is clearly an intrinsic property and not due to the size effect as reported for nano-wires or thin films of the same.