Triply‐Coupled Switching in 2D Ferroelastic Ferrimagnetic Metals

ABSTRACT Although significant progress has been made in devising approaches to control magnetism and spin polarization in 2D multiferroic systems, ferroelasticity, widely recognized as a fundamental ferroic order, has received far less attention compared with ferroelectricity. In this work, we constructed a general tight‐binding (TB) model that provides a universal framework for describing the ferroelastic switching in 2D ferrimagnetic metals. Based on this model and first‐principles calculations combined with a swarm‐intelligence structure‐search strategy, we identified an example, monolayer Nb 2 CN, which simultaneously exhibits ferroelasticity, ferrimagnetism, and metallicity. Interestingly, the system can present a triply‐coupled ( S , M , ε ) switching—reversible local spin splitting ( S ), net magnetization ( M ), and ferroelastic strain ( ε ). These spin‐magnetic‐lattice couplings inevitably lead to sign reversals in anomalous transport responses such as the anomalous Hall and magneto‐optical effects. These findings not only reveal a novel magnetoelastic coupling mechanism for triply‐coupled control of magnetism and spin polarization in 2D materials but also provide a promising platform for designing multifunctional spintronic devices.