Extremely large magnetoresistance in the hourglass Dirac loop chain metal \beta-ReO$_{2}$

TL;DR

This study reports an extremely large magnetoresistance in $eta$-ReO$_{2}$, a material with a complex Dirac loop chain structure, high electron density, and large Fermi surfaces, highlighting its potential for topological electronic applications.

Contribution

It demonstrates the connection between the Dirac loop chain structure and the observed large magnetoresistance in $eta$-ReO$_{2}$, supported by experimental and first-principles calculations.

Findings

22,000% magnetoresistance at 2 K and 10 T

High electron carrier density of 1×10^{22} cm^{-3}

Small Fermi surface linked to Dirac loop chain

Abstract

The transport and thermodynamic properties of $\beta$-ReO$_{2}$ crystallizing in a nonsymmorphic structure were studied using high-quality single crystals. An extremely large magnetoresistance (XMR) reaching 22,000 $\%$ in a transverse magnetic field of 10 T at 2 K was observed. However, distinguished from other topological semimetals with low carrier densities that show XMR, $\beta$-ReO$_{2}$ has a high electron carrier density of 1 $\times$ $10^{22}$ cm$^{-3}$ as determined by Hall measurements and large Fermi surfaces in the electronic structure. In addition, a small Fermi surface with a small effective mass was evidenced by de Haas-van Alphen oscillation measurements. The previous band structure calculations [S. S. Wang, et al., Nat. Commun. 8, 1844 (2017)] showed that two kinds of loops made of Dirac points of hourglass-shaped dispersions exist and are connected to each other by a point to form a string of alternating loops, called the Dirac loop chain (DLC), which are protected by the multiple glide symmetries. Our first-principles calculations revealed the complex Fermi surfaces with the smallest one corresponding to the observed small Fermi surface, which is just located near the DLC. The XMR of $\beta$-ReO$_{2}$ is attributed to the small Fermi surface and thus is likely caused by the DLC.