Speaker
Description
Bismuth/antimony-based chalcogenides such as $\mathrm{Bi_2Te_3}$, $\mathrm{BiSbTe_3}$, and $\mathrm{Sb_2Te_3}$ serve as prototypical compounds where the interplay of strong spin-orbit coupling$^[$$^1$$^]$ and crystal symmetry gives rise to both thermoelectric efficiency and topologically non-trivial surface states.$^[$$^2$$^]$$^[$$^3$$^]$ In this study, high-quality single crystals of these materials were synthesized via a modified Bridgman technique and comprehensively characterized using X-ray diffraction (XRD), SEM, TEM, and EDS.$^[$$^4$$^]$ Rietveld refinement of XRD data reveals a systematic variation in lattice parameters, with $a = b$ ranging from 4.27 $A^o$ in $\mathrm{Sb_2Te_3}$ to 4.38 $A^o$ in $\mathrm{Bi_2Te_3}$, and a corresponding unit cell volume expansion from 482.05 $A^o$$^3$ to 508.5 $A^o$$^3$, confirming successful isovalent doping and phase purity.
Temperature-dependent resistivity measurements ($4$K–$300$K) show metallic conduction in all samples, with clear Fermi liquid behavior below 50K. Fitting the low-temperature region to the expression $\rho = \rho_0 + AT^2$ yields coefficients $a$ ranging from 9.0 * $10^-$$^5$ to 20.5 * $10^-$$^5$ $\mu\Omega\cdot$cm/K$^2$, indicating enhanced electron-electron scattering in $\mathrm{Bi_2Te_3}$. Magnetoresistance (MR) measurements exhibit a prominent weak antilocalization (WAL) effect at low fields$^[$$^5$$^]$, which was quantitatively modeled using the Hikami–Larkin–Nagaoka (HLN) formalism. The $\alpha$ values, if around $-0.5$ to $-1$, confirm strong spin-orbit interaction with minimal magnetic scattering. Notably, $\mathrm{BiSbTe_3}$ displayed clear quantum oscillations resembling Shubnikov-de Haas behavior above 5T and a remarkably high MR of 140% at 2K and 9T, pointing to well-defined Fermi surfaces and high carrier mobility.
REFERENCES
[1] J. E. Moore, Nature 464, 194 (2010).
[2] L. Fu and C. L. Kane, Phys. Rev. B - Condens. Matter Mater. Phys. 76, 1 (2007).
[3] L. Fu, C. L. Kane, and E. J. Mele, Phys. Rev. Lett. 98,1 (2007).
[4] M. D. Anoop et al., Mater. Today Proc. 31, 616 (2019).
[5] H. K. Pal, V. I. Yudson, and D. L. Maslov, Phys. Rev.B Condens. Matter Mater. Phys. 85, 2 (2012).