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TT: Fachverband Tiefe Temperaturen

TT 74: Topological Insulators

TT 74.5: Vortrag

Donnerstag, 12. März 2026, 10:30–10:45, CHE/0091

Field-induced band modification and large magnetoresistance in topological-insulator Bi_1−xSb_x thin films — •E. Osmic^1,2, P. Bercoff³, F. Commeto³, Y. Skourski¹, F. Ganss⁴, J. Wosnitza^1,2, and J. Barzola Quiquia⁵ — ¹Hochfeld-Magnetlabor Dresden (HLD-EMFL), HZDR, Dresden, Germany — ²Institut für Festkörper- und Materialphysik, TU Dresden, Germany — ³Universidad Nacional de Córdoba, Córdoba, Argentina — ⁴Institut für Ionenstrahlphysik und Materialforschung, HZDR, Dresden, Germany — ⁵Felix-Bloch Institute for Solid-State Physics, Universität Leipzig, Germany

We studied the magnetic-field and temperature dependence of the electrical transport in topological-insulator Bi_1−xSb_x (x = 0.1, 0.15, 0.2) thin films. The resistivity ρ(T) shows a clear crossover between metallic surface transport at low temperatures and semiconducting bulk behavior at higher temperatures. Below 10 K, ρ(T) exhibits a characteristic two-dimensional electron–electron interaction contribution. Magnetoresistance measurements in pulsed magnetic fields up to 69 T reveal large, nonsaturating MR values reaching 2250 % over a broad temperature range. The full MR response can be consistently described using a modified two-band bulk model with field-dependent charge-carrier concentrations, complemented by a weak-antilocalization description of the surface states. These results highlight the possible field-induced band modification and the interplay between bulk and surface transport in Bi–Sb thin films.

Keywords: Magnetoresistance; Resistance; Raman spectroscopy