Large Magnetoresistance and Nontrivial Berry Phase in Nb3Sb Crystals with A15 Structure

TL;DR

This study reports the growth and characterization of Nb3Sb crystals, revealing large magnetoresistance and a nontrivial Berry phase, indicating topologically nontrivial semimetal properties with potential for Majorana mode research.

Contribution

First systematic measurement of magnetotransport and quantum oscillations in Nb3Sb crystals, demonstrating their topological nontriviality and large magnetoresistance.

Findings

Nb3Sb exhibits 717% magnetoresistance at 2K and 9T.

Hall measurements suggest perfect hole-electron compensation.

Nonzero Berry phase confirms topologically nontrivial band structure.

Abstract

Compounds with the A15 structure have attracted extensive attention due to their superconductivity and nontrivial topological band structure. We have successfully grown Nb$_3$Sb single crystals with a A15 structure and systematically measured the longitudinal resistivity, Hall resistivity and quantum oscillations in magnetization. Similar to other topological trivial/nontrivial semimetals, Nb$_3$Sb, exhibits large magnetoresistance (MR) at low temperatures (717$\%$, 2 K and 9 T), unsaturating quadratic field dependence of MR and up-turn behavior in $\rho_{xx}$(\emph{T}) curves under magnetic field, which is considered to result from a perfect hole-electron compensation, as evidenced by the Hall resistivity measurements. The nonzero Berry phase obtained from the de-Hass van Alphen (dHvA) oscillations demonstrates that Nb$_3$Sb is topologically nontrivial. These results indicate that Nb$_{3}$Sb superconductor is also a semimetal with large MR and nontrivial Berry phase, indicating that Nb$_{3}$Sb may be another platform to search for Majorana zero-energy mode.