Enhancing Magnetic Coupling in MN4-Graphene via Strain Engineering

Abstract

MN4-embedded graphene (MN4-G) layers, incorporating transition metal elements (M), represent a class of experimentally accessible two-dimensional materials with significant potential for stable nanoscale magnetization. In these systems, magnetic exchange interactions are primarily governed by Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling, exhibiting an anomalously prolonged decay of r to the power of (-n), where r is the M-M separation distance and n is between 0.5 and 2. This study investigates the impact of strain on the electronic and magnetic properties of MN4-G layers using ab-initio density functional theory (DFT). A novel strain-engineering approach is developed by applying controlled tension or compression to the layers. Our findings reveal that strain significantly modulates the strength, amplitude, and decay rate of the RKKY coupling. Notably, the CoN4-G layer demonstrates a pronounced enhancement in RKKY coupling strength, oscillation amplitude, and reduced decay rate under strain. Conversely, the CuN4-G layer exhibits distinct behavior, maintaining decoupled spin chains and invariant electronic and magnetic properties despite applied strain. This work underscores the tunability of magnetic interactions in MN4-G layers via strain engineering, providing insights into the design of strain-controlled magnetic materials for next-generation spintronic applications.