Crystal growth and characterization of bulk Sb₂Te₃ topological insulator

Abstract

The Sb 2 Te 3 crystals are grown using the conventional self flux method via solid state reaction route, by melting constituent elements (Sb and Te) at high temperature (850˚C), followed by slow cooling (2˚C/hour). As grown Sb 2 Te 3 crystals are analysed for various physical properties by X-ray diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDAX) and electrical measurements under magnetic field (6Tesla) down to low temperature (2.5K). The XRD pattern revealed the growth of synthesized Sb 2 Te 3 sample along (00l) plane, whereas the SEM along with EDAX measurements displayed the layered structure with near stoichiometric composition, without foreign contamination. The Raman scattering studies displayed known (A 1g 1 , E g 2 and A 1g 2 ) vibrational modes for the studied Sb 2 Te 3 . The temperature dependent electrical resistivity measurements illustrated the metallic nature of the as grown Sb 2 Te 3 single crystal. Further, the magnetotransport studies represented linear positive magneto-resistance (MR) reaching up to 80% at 2.5K under an applied field of 6Tesla.The weak anti localization (WAL) related low field (± 2Tesla) magneto-conductance at low temperatures (2.5K and 20K) has been analysed and discussed using the Hikami-Larkin -Nagaoka (HLN) model. Summarily, the short letter reports an easy and versatile method for crystal growth of bulk Sb 2 Te 3 topological insulator (TI) and its brief physical property characterization.

Flux free single crystal growth and detailed physical property characterization of Bi1−xSbx (x = 0.05, 0.1 and 0.15) topological insulator

“…The corresponding values of these four modes are displayed in Table 2. Interestingly, the four vibrational modes observed for Bi 1-x Sb x system differs from the pure (Bi 2 Te 3, Bi 2 Se 3 and Sb 2 Te 3 ) TI system (reported earlier by our own group), which exhibited only three distinct Raman peaks [37]. As reported, pure Bi and Sb exhibits two types of Raman active modes i.e., A 1g (upper frequency mode) and E g (lower frequency mode [38 -41].The A 1g mode is singly degenerate, whereas the E g mode is doubly degenerate.…”

“…Generally, materials with strong SOC exhibits positive MR value with WAL behaviour at lower temperatures and applied perpendicular magnetic fields [37,43,44]. In our present case, the possible reason for the coexistence of negative MR as well as WL behaviour might be due to the slight misalignment of the direction of the applied magnetic field and the transport current.…”

“…Figure 10 (a, b, c) is the characteristic magnetic field and l φ is the phase coherence length. As reported, for single surface conducting channel ⍺ should exhibit a value of -0.5, whereas for multi parallel conducting channels ⍺ value lies between -0.5 to -1.5 [37,[46][47][48][49]. However, experimental values of ⍺ is reported to lie between -0.4 and -1.1, for single surface state, two surface states, or intermixing between the surface and bulk states [37,[46][47][48][49].…”

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

“…To understand the impact of Co doping on the phonon dynamics of Bi 2 Se 3 single crystal, we performed Raman spectroscopy measurements at room temperature of both [46,47]. shows the normalised ( / 250K ) resistivity as a function of temperature from 250K down to 5K.…”

Hikami-Larkin-Nagaoka (HLN) Treatment of the Magneto-Conductivity of Bi2Te3 Topological Insulator

“…Higher the temperature, lower the coherence length ( ). Recently, some of us reported detailed crystal growth and physical property characterization of one of the popular TI i.e., Bi 2 Te 3 [19,20]. Keeping in view the importance of the overall conduction process of a TI in terms of competing WAL and WL, in current short article, we report the HLN treatment of the magneto conductivity of our well characterized [19,20] Bi 2 Te 3 single crystal.…”