Theoretical and experimental investigation of magnetic properties of iodine and cerium Co-doped Bi2Te3 nanoparticles

Abstract

A long-range magnetic order in the topological insulator (Bi2Te3) achieved a great interest by the doping of magnetic elements on to Bi and Te-sites. The magnetic moments can be introduced by adding trivalent rare-earth elements such as Ce and I. In this report, Bi2Te3, Ce0.2Bi1.8Te3, and Ce0.2Bi1.8Te2.9I0.1 nanoparticle were synthesized by the novel low-temperature double solvent sol-gel technique. The co-doped nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), physical properties measurement system (PPMS), and vibrating sample measurement system (VSM). The VSM studies showed that the magnetization (M) of pure Bi2Te3 sample was successfully increased by adding iodine onto the Ce-doped sample (Ce0.2Bi1.8Te2.9I0.1). For in-depth analysis, PPMS results revealed that the as-synthesized samples exhibit paramagnetic nature which then exchange into antiferromagnetic behavior after substituting Ce I onto Bi2Te3, at a varying temperature range from 0 to 400K. The density functional theory (DFT) was also performed to understand the exchange-biased phenomenon for as-synthesized samples. Moreover, the experimental results can predict that the magnetic samples synthesized by the novel double solvent sol-gel method can provide magnetic materials with large remnant magnetization compared with the pure Bi2Te3.