Signature of two-dimensional conduction on crystal surface of Mott insulator NiS₂

Exploring low-dimensional electronic states is a frontier in condensed matter physics, particularly in systems with insulating bulks and conducting surfaces. NiS_2 is a prototypical Mott insulator where macroscopic surface conduction has long been observed, yet its microscopic transport dimensionality (1D vs. 2D) remains an ongoing debate. This work addresses this puzzle by providing transport signatures that support an intrinsic 2D origin for this behavior. Below T^\ast \sim 100 K, the resistivity develops a plateau conforming to a 2D Mott-type variable-range hopping. Simultaneously, the angle-dependent magnetoresistance reveals symmetries consistent with the (001) surface lattice, suggesting 2D transport rather than oriented 1D channels. This 2D character is further supported by the resilience of surface conduction under slight doping-induced disorder, in contrast to inherently unstable 1D systems. These findings help understand the physical origin of the surface transport mechanism in Mott insulator NiS_2.