Unsaturated both large positive and negative magnetoresistance in Weyl Semimetal TaP

TL;DR

This study reports extremely large positive and negative magnetoresistance in Weyl semimetal TaP, revealing unique electronic properties, high mobility, and nontrivial Berry phase, with potential for fundamental physics insights and applications.

Contribution

We demonstrate that TaP exhibits unprecedented magnetoresistance behavior and nontrivial Berry phase, advancing understanding of Weyl semimetals and their potential uses.

Findings

Magnetoresistance reaches 328,000% at 2K and 176% at 300K in 8T.

Negative MR of -3000% observed with magnetic field parallel to electric field.

TaP shows a nontrivial Berry phase of 0.3958, indicating Weyl fermion characteristics.

Abstract

After growing successfully TaP single crystal, we measured its longitudinal resistivity (rhoxx) and Hall resistivity (rhoyx) at magnetic fields up to 9T in the temperature range of 2-300K. It was found that at 2K its magnetoresistivity (MR) reaches to 328000 percent, at 300K to 176 percent at 8T, and both do not appear saturation. We confirmed that TaP is indeed a low carrier concentration, hole-electron compensated semimetal, with a high mobility of hole muh=371000 cm2V-1s-1, and found that a magnetic-field-induced metal-insulator transition occurs at room temperature. Remarkably, as a magnetic field (H) is applied in parallel to the electric field (E), the negative MR due to chiral anomaly is observed, and reaches to -3000 percent at 9T without any signature of saturation, too, which distinguishes with other Weyl semimetals (WSMs). The analysis on the Shubnikov-de Haas (SdH) oscillations superimposing on the MR reveals that a nontrivial Berry phase with strong offset of 0.3958 realizes in TaP, which is the characteristic feature of the charge carriers enclosing a Weyl nodes. These results indicate that TaP is a promising candidate not only for revealing fundamental physics of the WSM state but also for some novel applications.