Features of thermomagnetic transport due to the superconducting interfaces in inclination bicrystals of Bi and 3D topological insulator Bi1-xSbx

Abstract

We studied the thermomagnetic power Sii (B) and Nernst–Ettingshausen effect Sij (B) in inclination bicrystals of Bi and 3D topological insulator Bi1−xSbx (0.04 < x ≤ 0.12) with superconducting nano-width interfaces (Tc ≤ 21 K). High values of thermomagnetic effects in small disorientation angle (SDA) bicrystals far exceeding values in single-crystalline samples were found. It was established that Sii (B) linearly increases in high fields without saturation and change the sign from negative in positive in bicrystals of 3D Dirac point forming (x ∼ 0.04), specifying the signature of 3D topological semimetal. Contrarily, Sii (B) in LDA bicrystals with 0.06 ≤ x ≤ 0.12 undergoes saturation or increases smoothly, the Landau level index depends linearly on 1/Bn, and extrapolate to – 0.5 if 1/Bn → 0, what is typical for the 3D topological insulators. Two new quantum oscillation harmonics are reviled in high fields; they characterize different densities of electronic states and different levels of disorder at LDA and SDA interfaces.