Anisotropic upper critical field, Seebeck and Nernst coefficient of Nb_0.20Bi₂Se₃ superconductor

Abstract

We present the magneto-transport and the thermoelectric (Seebeck and Nernst coefficient) studies of the Nb-doped Bi2Se3 topological superconductor. The angle-dependent magnetoresistance study highlights the anisotropy of upper critical field (Hc2) for in-plane and out-of-plane magnetic field orientation with the anisotropy parameter Γ ~1.3. The estimated value of the carrier concentration (~1019 cm-3) for Nb0.20Bi2Se3 is one order larger than for Bi2Se3. Doping of Nb shows a significant decrease in the Seebeck coefficient value and the estimated Fermi temperature of the three-dimensional Fermi surface at the centre of Brillouin zone in the zero-temperature limit enhances by ~4 times in comparison to pristine Bi2Se3 . We have observed a large value (~2.3 μV K-1 T-1) of Nernst coefficient for Bi2Se3 at room temperature which decreases with Nb doping (~0.5 μV K-1 T-1).

Magneto-transport and thermoelectric studies of antiperovskite semimetal: Mn3SnC

“…It is found that sharp drop is independent of the magnetic field. The existence of Dirac dispersion bands at the Fermi level can produce large value of Nernst signal [53]. The Nernst signal of Bi 2 Se 3 is proposed 2.3 µV K −1 T −1 [53] and Mn 3 SnC show maximum value ∼3.5 µV K −1 T −1 around 50 K at 8 T field.…”

“…The existence of Dirac dispersion bands at the Fermi level can produce large value of Nernst signal [53]. The Nernst signal of Bi 2 Se 3 is proposed 2.3 µV K −1 T −1 [53] and Mn 3 SnC show maximum value ∼3.5 µV K −1 T −1 around 50 K at 8 T field. It is to note that Nernst coefficient can be of any sign, without any direct relation to carrier type.…”

“…The Nernst effect offers a way to understand properties of topological materials. The Nernst signal provides information on small unusual contributions, including extrinsic contributions from magnetic impurity scattering and intrinsic contributions from Berry curvature [53,54]. Around T C , spin fluctuations have more significant impact, resulting in Nernst signal exhibits drastic change with the field.…”

Two-fold anisotropic superconducting state in topological superconductor Sn4Au

“…Sn 4 Au lacks theoretical and experimental reports that could explain the observed two-fold anisotropic superconducting properties in the same. Topological superconducting materials are reported to show both in and out-of-plane anisotropic superconducting state due to breaking crystalline symmetry in the same [3,[20][21][22][23][24]33,34]. The other layered superconductors [35] are also found to show a similar feature as well.…”

Nernst and seebeck effects in α−T3 lattice

“…Thermal potential can serve as a sensitive probe of transport properties, providing complementary information to resistivity [33][34][35][36]. Recently, the Nernst and Seebeck effects have been studied in various systems [37][38][39][40][41][42][43]. At high temperatures, the direct measurement of the Seebeck coefficient S c can be compared with the results of the calculation using the Mott relation [44].…”