Flux free single crystal growth and detailed physical property characterization of Bi_1−xSb_x (x = 0.05, 0.1 and 0.15) topological insulator

Abstract

Here, we report the crystal growth, physical and transport properties of Bi 1-x Sb x (x = 0.05, 0.1 and 0.15) topological insulator. Single crystals of Bi 1-x Sb x (x = 0.05, 0.1 and 0.15) were grown by melting bismuth and antimony together using the facile self flux method. The XRD measurements displayed highly indexed 00l lines and confirmed the crystalline nature as well as the rhombohedral structure of the Bi 1-x Sb x (x = 0.05, 0.1 and 0.15) crystals. Raman spectroscopy measurements for Bi 1-x Sb x system revealed four peaks within the spectral range of 10 to 250 cm -1 namely A 1g and E g modes corresponding to Bi-Bi and Sb-Sb vibrations. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) measurements showed the layered surface morphology and near stoichiometric chemical composition of Bi 1-x Sb x (x = 0.05, 0.1 and 0.15) crystals. Furthermore, EDAX mapping confirmed the homogeneous distribution of Bi and Sb elements. Temperature dependent electrical resistivity curves with and without applied magnetic field exhibited a metallic behaviour and linear non-saturating magneto-resistance (MR) respectively for all the antimony (Sb) concentrations of x = 0.05, 0.1 and 0.15. The lowest Sb concentration sample with x = 0.05 (Bi 0.95 Sb 0.05 ) exhibited the highest MR value of about 1400%, followed by x = 0.1 and 0.15 samples (Bi 0.9 Sb 0.1 and Bi 0.85 Sb 0.05 ) with MR values reaching up to 500% and 110% respectively at 2K and 6Tesla applied field. Also, a coexistence of negative MR and WAL/WL behaviour is observed at lower magnetic fields (below ± 0.2Tesla) in Bi 0.9 Sb 0.1 and Bi 0.85 Sb 0.05 system. To further elaborate the transport properties of Bi 1-x Sb x (x = 0.05, 0.1 and 0.15), the magneto-conductivity (MC) is fitted to the HLN (Hikami Larkin Nagaoka) equation and it is found that the charge conduction mechanism is mainly dominated by WAL (weak anti-localization) along with a small contribution from WL (weak localization) effect. Summarily, the short letter discusses the synthesis, interesting transport and magnetotransport properties of Bi 1-x Sb x (x = 0.05, 0.1 and 0.15), which could be useful in understanding the fascinating properties of topological insulators and their technological applications.

Shubnikov-De Haas (Sdh) Oscillation in Self-Flux Grown Rhombohedral Single-Crystalline Bismuth

“…Further, to investigate the growth direction of grown crystal, XRD spectra were recorded on mechanically cleaved flake, which reveals that Bi crystallized along (00l) diffraction plane with l = 3n (n = 1,2,3…) as shown in figure 2(b). An additional peak at 2θ = 48.82° is also observed, which may be due to the misalignment of the crystal, as mentioned in the literature 43 . The Rietveld refined parameters were used to draw Bi unit cells using VESTA software, as shown in the inset of Fig.…”

“…High purity (99.999%) bismuth (Bi) powder was taken to grow Bi single crystal using the self-flux method via solid-state reaction route 43 . The Bi powder was pelletized into a rectangular pellet using a hydraulic press and vacuum-sealed into a quartz tube with a pressure of 10 -5 mbar.…”

“…Further, the ampoule was cooled down to 245°C and kept there for another 73h; finally, it was allowed to cool down to room temperature with a cooling rate of 120°C/h, see for more details ref. 43. Figure 1 shows the detailed heat treatment, and the inset image shows the obtained silvery shiny Bi crystal of size ≈ 1cm×0.5cm.…”

Surface states induced weak anti-localization effect in Bi0.85Sb0.15 topological single crystal

“…The binary mixture then pelletized and sealed into an evacuated quartz tube. The single crystals were grown by following the heat treatment as reported earlier [17]. The quartz tube was heated to 650 °C, and kept hold for 8 h in order to get homogenized mixture.…”

High field magneto-transport of mixed topological insulators Bi2Se3-xTex (x = 0, 1, 2 & 3)

“…While the resistivity-temperature (ρ-T) characteristics of all the samples correspond to the metallic behaviour i.e., resistivity decreases with a decrease in temperature. The Residual Resistivity Ratio (RRR) [28,29] value which is taken as the ratio of resistivity at room temperature and 10K ( ρ 230K ρ 10K ⁄ ) is equal to 2.67 for Bi2Se3, 1.75 for Bi2Se2Te1, 3.51 for Bi2Se1Te2 and 10.65 for Bi2Te3 TI crystals. Larger the RRR value, the higher will be the crystalline quality of the sample [30].…”