Evolution of giant exchange bias with ferromagnetic ordering and a robust memory effect by strain engineering MoS2 in weak antiferromagnetic gating

Abstract

The emergence of 2D ferromagnetism in MoS₂ layers induced by an inherently non-magnetic material like NiOOH is an interesting area of research. This result is of widespread technological importance if additionally associated with magnetic exchange correlations that show promising memory effects. In this work, we show that a giant exchange bias is housed within highly strained 2D MoS₂ multilayers by interfacing with the thin weakly antiferromagnetic β-NiOOH phase. The robustness and magnitude of such zero-field-cooled exchange bias emerge from the unique sublattice spin configuration of β-NiOOH, which serves as a source of surface uncompensated moments, while highly strained 2D MoS₂ acts as an active pinning layer in the hybrid. The exchange coupling between the weak antiferromagnetic layer and the adjacent moment-induced ferromagnetic layer is strong enough to show a near-room temperature thermoremanent (TRM) memory effect in magnetization states, which is newly observed for 2D hybrid materials. Upon manifesting the vertical type junction, this hybrid material also shows non-volatile electrical bistable states with a low operating bias voltage (1.25 V) and high ON/OFF ratio (6 × 10²), along with hysteretic magnetoresistance, which can be useful in 2D-based spintronic applications. First-principles calculations also verified such charge transfer interactions at the interface of the hybrid structure.