Large nonsaturating magnetoresistance and signature of non-degenerate Dirac nodes in ZrSiS

TL;DR

This study reports large nonsaturating magnetoresistance and Dirac fermion signatures in ZrSiS, demonstrating robust linear dispersion and non-degenerate Dirac nodes up to 2 eV, with implications for topological materials.

Contribution

It provides the first comprehensive magnetotransport analysis of ZrSiS, confirming Dirac fermions and chiral anomaly in a material with exceptionally robust linear dispersion.

Findings

Large non-saturating magnetoresistance (~1.4×10^5% at 2K, 9T)

Observation of non-trivial π Berry phase indicating Dirac fermions

Detection of Adler-Bell-Jackiw chiral anomaly

Abstract

While the discovery of Dirac and Weyl type excitations in electronic systems is a major breakthrough in recent condensed matter physics, finding appropriate materials for fundamental physics and technological applications, is an experimental challenge. In all the reported materials, linear dispersion survives only up to a few hundred meV from the Dirac or Weyl nodes. On the other hand, real materials are subject to uncontrolled doping during preparation and thermal effect near room temperature can hinder the rich physics. In ZrSiS, ARPES measurements have shown an unusually robust linear dispersion (up to $\sim$2 eV) with multiple non-degenerate Dirac nodes. In this context, we present the magnetotransport study on ZrSiS crystal, which represents a large family of materials (\textit{WHM} with \textit{W} = Zr, Hf; \textit{H} = Si, Ge, Sn; \textit{M} = O, S, Se, Te) with identical band topology. Along with extremely large and non-saturating magnetoresistance (MR), $\sim$ 1.4 $\times$ 10$^{5}$ \% at 2 K and 9 T, it shows strong anisotropy depending on the direction of the magnetic field. Quantum oscillation and Hall effect measurements have revealed large hole and small electron Fermi pockets. Non-trivial $\pi$ Berry phase confirms the Dirac fermionic nature for both types of charge carriers. The long-sought relativistic phenomenon of massless Dirac fermions, known as Adler-Bell-Jackiw chiral anomaly, has also been observed.