Dirac Fermions and Possible Weak Antilocalization in LaCuSb$_{2}$

TL;DR

This study provides experimental evidence of Dirac fermions in LaCuSb$_{2}$ through ARPES, quantum oscillations, and magnetoresistance, revealing topologically non-trivial electronic properties in a layered square-lattice compound.

Contribution

First observation of Dirac fermions in LaCuSb$_{2}$ using ARPES and quantum oscillations, highlighting its potential as a topological material.

Findings

Linearly dispersing bands observed in ARPES.

Weak antilocalization effects in magnetoresistance.

Low effective mass electrons (~0.065m_e) confirming Dirac fermions.

Abstract

Layered heavy-metal square-lattice compounds have recently emerged as potential Dirac fermion materials due to bonding within those sublattices. We report quantum transport and spectroscopic data on the layered Sb square-lattice material LaCuSb$_{2}$. Linearly dispersing band crossings, necessary to generate Dirac fermions, are experimentally observed in the electronic band structure observed using angle-resolved photoemission spectroscopy (ARPES), along with a quasi-two-dimensional Fermi surface. Weak antilocalization that arises from two-dimensional transport is observed in the magnetoresistance, as well as regions of linear dependence, both of which are indicative of topologically non-trivial effects. Measurements of the Shubnikov-de Haas (SdH) quantum oscillations show low effective mass electrons on the order of 0.065$m_{e}$, further confirming the presence of Dirac fermions in this material.