Electronic structure and open-orbit Fermi surface topology in isostructural semimetals NbAs$_2$ and W$_2$As$_3$ with extremely large magnetoresistance

TL;DR

This study uses angle-resolved photoemission spectroscopy to map the electronic structures of NbAs$_2$ and W$_2$As$_3$, revealing open-orbit Fermi surface topologies that may explain their extremely large magnetoresistance.

Contribution

It provides the first direct visualization of the three-dimensional electronic structures of NbAs$_2$ and W$_2$As$_3$, linking open-orbit Fermi surfaces to the XMR effect in these semimetals.

Findings

Open-orbit Fermi surfaces observed in NbAs$_2$ and W$_2$As$_3$.

Open Fermi surface topology may be common in XMR materials with space group C12/m1.

Open-orbit Fermi surfaces could contribute to the origin of XMR.

Abstract

In transition-metal dipnictides $TmPn_2$ ($Tm$ = Ta, Nb; $Pn$ = P, As, Sb), the origin of extremely large magnetoresistance (XMR) is yet to be studied by the direct visualization of the experimental band structures. Here, using angle-resolved photoemission spectroscopy, we map out the three-dimensional electronic structure of NbAs$_2$. The open-orbit topology contributes to a non-negligible part of the Fermi surfaces (FSs), like that of the isostructural compound MoAs$_2$, where the open FS is proposed to likely explain the origin of XMR. We further demonstrate the observation of open characters in the overall FSs of W$_2$As$_3$, which is also a XMR semimetal with the same space group of $C$12/$m$1 as $TmPn_2$ family and MoAs$_2$. Our results suggest that the open-orbit FS topology may be a shared feature between XMR materials with the space group of $C$12/$m$1, and thus could possibly play a role in determining the corresponding XMR effect together with the electron-hole compensation.