Weak Antilocalization and Quantum Hall Effect in Bulk CaCuSb Single Crystal

The quantum Hall effect (QHE) in 3D solids is relatively unexplored in experiments due to the limited choice of viable candidate materials. Here, we report on the observation of weak antilocalization (WAL) and QHE followed by Shubnikov de-Haas (SdH) oscillations with oscillation frequency 314 T in bulk CaCuSb single crystal which crystallizes in the hexagonal structure (P6₃/mmc). One of the unique features of this crystal structure is that it possesses two Cu-Sb layers in the unit cell which act as the conduction channels. Significant anisotropy in electrical transport measurements along crystallographic a- and c- direction suggests the magneto-transport effect is due to charge diffusion on Cu-Sb planes but not along c- axis. A cusp like behavior in the low field region of magnetoresistance reveals WAL in this compound, as observed in ABC- type hexagonal structure CaAgBi ^[1]. Quantized Hall plateaus are observed in 1/ρ_xy vs 1/B plot which is attributed to the multiple 2D conduction channels in the system. First-principles calculations show that CaCuSb is a semimetal with dominant hole carriers at the Fermi level. Our study shows that CaCuSb can provide a unique platform to study QHE in high magnetic fields.

Ref- [1] Souvik Sasmal et al., J. Phys.: Condens. Matter 32, 335701 (2020)