Growth, Characterization and High Field Magneto-Conductivity of Co0.1Bi2Se3 Topological Insulator

TL;DR

This study investigates the growth, structural, and magneto-transport properties of Co-doped Bi2Se3 topological insulator crystals, revealing surface-dominated conduction, magnetic ordering, and changes in magneto-resistance due to cobalt addition.

Contribution

It provides new insights into the effects of cobalt doping on the structural, magnetic, and transport properties of Bi2Se3 topological insulators, including magneto-conductivity analysis and magnetic behavior characterization.

Findings

Cobalt doping increases lattice parameters and Raman shifts.

Magneto-resistance decreases with Co addition, indicating altered surface conduction.

Co-doped Bi2Se3 exhibits ferromagnetic and diamagnetic behavior depending on the measurement technique.

Abstract

We report the crystal growth as well as transport properties of Co added Bi2Se3 single crystals. The values of the lattice parameters a and b for Co added sample were observed to increase as compared to the pure Bi2Se3. The Raman spectroscopy displayed higher Raman shift of corresponding vibrational modes for Co0.1Bi2Se3, and the resistivity curves with and without applied magnetic field shows a metallic behaviour. Both the crystals were subjected to magneto-resistance (MR) measurements under applied fields of 14Tesla. The value of MR is found to decrease from about 380 (5K, 14 Tesla) for Bi2Se3 to 200 degree for Co0.1Bi2Se3. To elaborate the transport properties of pure and Co added Bi2Se3 crystals, the magneto-conductivity is fitted to the HLN (Hikami Larkin Nagaoka) equation and it is found that the charge conduction is mainly dominated by surface driven WAL (weak anti-localization) with negligible bulk WL (weak localization) contribution in both crystals alike. The MH curves of Co0.1Bi2Se3 crystal at different temperatures displayed a combination of both ferromagnetic and diamagnetic behaviour. On the other hand, the Electron Paramagnetic Resonance (EPR) revealed that pure Bi2Se3 is diamagnetic whereas, Co orders ferro-magnetically with resonating field around 3422Oe at room temperature.