Extremely high magnetoresistance and conductivity in the type-II Weyl semimetals WP2 and MoP2

Nitesh Kumar,Horst Borrmann,Binghai Yan,Nan Xu,Claudia Felser,Mengyu Yao,Chandra Shekhar,Tobias Förster,Ming Shi,Uli Zeitler,Kaustuv Manna,Olga Young,Vicky Süss,Inge Leermakers,Marcus Schmidt,Yan Sun

doi:10.1038/s41467-017-01758-z

Abstract

The peculiar band structure of semimetals exhibiting Dirac and Weyl crossings can lead to spectacular electronic properties such as large mobilities accompanied by extremely high magnetoresistance. In particular, two closely neighboring Weyl points of the same chirality are protected from annihilation by structural distortions or defects, thereby significantly reducing the scattering probability between them. Here we present the electronic properties of the transition metal diphosphides, WP2 and MoP2, which are type-II Weyl semimetals with robust Weyl points by transport, angle resolved photoemission spectroscopy and first principles calculations. Our single crystals of WP2 display an extremely low residual low-temperature resistivity of 3 nΩ cm accompanied by an enormous and highly anisotropic magnetoresistance above 200 million % at 63 T and 2.5 K. We observe a large suppression of charge carrier backscattering in WP2 from transport measurements. These properties are likely a consequence of the novel Weyl fermions expressed in this compound.

Highlights

The peculiar band structure of semimetals exhibiting Dirac and Weyl crossings can lead to spectacular electronic properties such as large mobilities accompanied by extremely high magnetoresistance
The space group symmetry of WP2 is very similar to the two dimensional WTe2 which contains a mirror-plane, a glide-plane and a two-fold screw axis[13]
We focus on the electronic properties of WP2 and the data of MoP2 are mostly included in the Supplementary Information

Summary

Introduction

The peculiar band structure of semimetals exhibiting Dirac and Weyl crossings can lead to spectacular electronic properties such as large mobilities accompanied by extremely high magnetoresistance. We observe a large suppression of charge carrier backscattering in WP2 from transport measurements These properties are likely a consequence of the novel Weyl fermions expressed in this compound. For a compound to display Weyl points it must exhibit either inversion symmetry breaking, as in, for example, TaAs8, or time reversal symmetry breaking, as in, for example, GdPtBi21,22. In these compounds, the Weyl points (WPs) of opposite chirality are close to each other and, are vulnerable to annihilation from structural distortions or defects.

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Conclusion