Robust Electric‐Field Control of Colossal Exchange Bias in CrI3 Homotrilayer

Abstract Controlling exchange bias (EB) by electric fields is crucial for next‐generation magnetic random access memories and spintronics with ultralow energy consumption and ultrahigh speed. Multiferroic heterostructures have been traditionally used to electrically control EB and interfacial ferromagnetism through weak/indirect coupling between ferromagnetic and ferroelectric films. However, three major bottlenecks (lattice mismatch, interface defects, and weak/indirect coupling in multiferroic heterostructures) remain, resulting in only a few tens of milli‐tesla EB field. Here, this study reports a robust electric‐field control recipe to dynamically tailor the EB effect in a pure CrI 3 homotrilayer on a ferroelectric Y‐doped HfO 2 (HYO) substrate, and demonstrate a colossal and tunable EB field ( H E ) from −0.15 to +0.33 T, giving rise to an EB modulation of 0.48 T. The charge doping due to ferroelectric HYO film divides a homo‐configuration of CrI 3 homotrilayer into one antiferromagnetic (AFM) bilayer CrI 3 and one ferromagnetic (FM) monolayer CrI 3 , favoring direct exchange coupling. The synergies of charge doping and electric field induce a transition of magnetic orders from AFM to FM phase in bilayer CrI 3 , which is also supported by first‐principles calculations, leading to the robust electric control of colossal EB effect. The results therefore open numerous opportunities for exploring 2D spintronics, memories, and braininspired in‐memory computing.