Nonvolatile bistable planar Hall effects in a natural two-dimensional metal–antiferromagnet heterostructure

Antiferromagnetic materials with van der Waals (vdW) layered structures hold great promises for developing the next generation of electronic and optoelectronic devices, providing unique combinations of terahertz spin dynamics, ultrastability against magnetic fields disturbance, and low power consumption. Here, we demonstrate unconventional nonvolatile bistable planar Hall effect (PHE) in few-layer ${\mathrm{GdTe}}_{3}$, a natural vdW heterostructure consisting of metallic Te layers and antiferromagnetic (AFM) GdTe bilayers. By fully unfolding the magnetic phase diagram of few-layer ${\mathrm{GdTe}}_{3}$ utilizing temperature- and angle-dependent magnetotransport measurements, we identify that the nonvolatile switching of bistable PHE states is rooted in the fourfold N\'eel vector flipping between two perpendicular in-plane magnetocrystalline anisotropy axes, each flipping reverses the signs of the PHE state. The efficient magnetic field ($H$) write-in and zero-field read out of the PHE memory pave the way for 2D AFM-based spintronics such as nonvolatile information storage and logic operations.