Electrical, Thermal and Spectroscopic Characterization of Bulk Bi2Se3 Topological Insulator

Abstract

We report electrical (angular magneto-resistance, and Hall), thermal (heat capacity) and spectroscopic (Raman, x-ray photo electron, angle resolved photo electron) characterization of bulk Bi 2 Se 3 topological insulator, which is being is grown by self flux method through solid state reaction from high temperature (950˚C) melt and slow cooling (2˚C/hour) of constituent elements. Bi 2 Se 3 exhibited metallic behaviour down to 5K. Magneto transport measurements revealed linear up to 400% and 30% MR at 5K under 14 Tesla field in perpendicular and parallel field direction respectively. We noticed that the magneto-resistance (MR) of Bi 2 Se 3 is very sensitive to the angle of applied field. MR is maximum when the field is normal to the sample surface, while it is minimum when the field is parallel. Hall coefficient (R H ) is seen nearly invariant with negative carrier sign down to 5K albeit having near periodic oscillations above 100K. Heat capacity (C p ) versus temperature plot is seen without any phase transitions down to 5K and is well fitted (Cp = γT + βT 3 ) at low temperature with calculated Debye temperature (Ѳ D ) value of 105.5K. Clear Raman peaks are seen at 72, 131 and 177 cm -1 corresponding to A 1g 1 , E g 2 and A 1g 2 respectively. Though, two distinct asymmetric characteristic peak shapes are seen for Bi 4f 7/2 and Bi 4f 5/2 , the Se 3d region is found to be broad displaying the overlapping of spin -orbit components of the same. Angle-resolved photoemission spectroscopy (ARPES) data of Bi 2 Se 3 revealed distinctly the bulk conduction bands (BCB), surface state (SS), Dirac point (DP) and bulk valence bands (BVB) and 3D bulk conduction signatures are clearly seen. Summarily, host of physical properties for as grown Bi 2 Se 3 crystal are reported here.

Modeling of magneto-conductivity of bismuth selenide: a topological insulator

“…1g , E 2 g , and A 2 1g respectively [30]. The SEM image confirms the layered structure of the topological single crystal.…”

“…The recorded pattern confirms the unidirectional growth of Bi 2 Se 3 crystals along the (00l) plane. The single crystal has a rhombohedral crystal structure and having R3m space group, as described in our previous report [30]. The insets of Fig.…”

“…The powders were mixed thoroughly in the inert (Argon) atmosphere and pelletized into a rectangular pellet with a high vacuum of 10 -5 mbar using a rotary and diffusion pump system. It was kept in an auto programmable furnace with optimized heat treatment, described in our previous report [31]. The obtained crystal was mechanically cleaved for further characterization measurements.…”

Exploration of terahertz from time-resolved ultrafast spectroscopy in single-crystal Bi2Se3 topological insulator

“…It can be seen in fig. 3(c), that this TI contains three bi-layers of Bi and Se stacked monolayers of either Bi or Se in a closely packed FCC lattice structure [38,39]. between acoustic phonons and electrons gives rise to a slow component of several picoseconds [14,16,17,20].…”

“…Single crystal of Bi2Se3 TI is grown by a solid-state reaction route. The purest form (>4N) of Bi (Bismuth) and Selenium (Se) were taken as precursor to the grow the crystal via the self-flux method [38,39]. The encapsulated weighed and inert atmosphere well ground rectangular bar sample was kept in a fully automated tube furnace under a well optimized heat treatment as described in fig 1(a) [34,35].…”