8–12 Jul 2025
Politechnica Univ
Europe/Bucharest timezone

Low-Temperature Transport and Magnetoresistance in Bismuth Chalcogenide Topological Insulators

11 Jul 2025, 09:20
20m
Politechnica Univ

Politechnica Univ

Splaiul Independenței 313, București 060042
Oral Presentations S03 – Condensed matter, Materials and Applied Physics Condensed Matter, Materials and Applied Physics

Speaker

Ayush R. Mokashi (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.)

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).

Primary authors

Mr Nabarun Bera (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.) Ayush R. Mokashi (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.)

Co-authors

Dr Anoop M.D. (Department of Advanced Science and Technology, Toyota Technological Institute, Nagoya, Aichi 468-8511, Japan.) Mr Sachin Sharma (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.) Ms Nisha Yadav (Malla Reddy Engineering College for Women Maisammaguda, Secunderabad (500100), India.) Ms Deepika Kanwar (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.) Dr Balram Tripathi (S. S. Jain Subodh PG (Autonomous) College Jaipur (302004), India.) Dr Dinesh K. Shukla (UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore (452017), India) Dr Manoj Kumar (Department of Physics, Malaviya National Institute of Technology Jaipur (302017), India.)

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