Giant Tunneling Magnetoresistance in Graphene/$h$-BN Based van der Waals Magnetic Tunnel Junctions via 3$d$ Transition Metal Intercalation

TL;DR

This paper proposes a method to create highly efficient 2D magnetic tunnel junctions using transition metal-intercalated graphene and h-BN barriers, achieving record-high tunneling magnetoresistance for advanced spintronic devices.

Contribution

It introduces a novel strategy for constructing fully 2D magnetic tunnel junctions with giant TMR by intercalating transition metals in graphene, supported by first-principles calculations.

Findings

Achieved giant TMR of 4.35 x 10^8% in Mn-graphene/h-BN system.

Observed TMR oscillations with barrier thickness, indicating quantum tunneling effects.

Enhanced TMR to 10^9% under biaxial strain in Mn-graphene systems.

Abstract

Atomic intercalation offers a powerful route for engineering two-dimensional (2D) materials by precisely tuning interlayer electronic coupling and spin configurations. Here, we propose a generic strategy for the construction of fully 2D magnetic tunnel junctions (MTJs) based on transition metal-intercalated graphene electrodes with $h$-BN barrier layer. First-principles calculations reveal that intercalation not only stabilizes uniform atomic dispersion via steric hindrance but also induces robust ferromagnetism in graphene. Manganese- and vanadium-intercalated systems (Mn-Gr and V-Gr) exhibit exceptional spintronic performance, with tunneling magnetoresistance (TMR) showing a pronounced odd-even oscillation as a function of barrier thickness. A giant TMR of $4.35 \times 10^8\,\%$ is achieved in the Mn-Gr system with a monolayer barrier $h$ -BN ($n=1$), while V-Gr reaches a maximum TMR of $1.86 \times 10^5\,\%$ for a trilayer barrier ($n=3$). Moreover, biaxial strain further enhances the TMR to $10^9\,\%$ and $10^7\,\%$ in Mn-Gr and V-Gr systems, respectively. The devices also exhibit perfect spin filtering and pronounced negative differential resistance, offering new opportunities for high-performance spintronic and memory applications based on 2D van der Waals heterostructures.