Fabrication-induced even-odd discrepancy of magnetotransport in few-layer MnBi₂Te₄.

Abstract

The van der Waals antiferromagnetic topological insulator MnBi₂Te₄ represents a promising platform for exploring the layer-dependent magnetism and topological states of matter. Recently observed discrepancies between magnetic and transport properties have aroused controversies concerning the topological nature of MnBi₂Te₄ in the ground state. In this article, we demonstrate that fabrication can induce mismatched even-odd layer dependent magnetotransport in few-layer MnBi₂Te₄. We perform a comprehensive study of the magnetotransport properties in 6- and 7-septuple-layer MnBi₂Te₄, and reveal that both even- and odd-number-layer device can show zero Hall plateau phenomena in zero magnetic field. Importantly, a statistical survey of the optical contrast in more than 200 MnBi₂Te₄ flakes reveals that the zero Hall plateau in odd-number-layer devices arises from the reduction of the effective thickness during the fabrication, a factor that was rarely noticed in previous studies of 2D materials. Our finding not only provides an explanation to the controversies regarding the discrepancy of the even-odd layer dependent magnetotransport in MnBi₂Te₄, but also highlights the critical issues concerning the fabrication and characterization of 2D material devices.