Screening intrinsic ferroelastic altermagnets in NiAs-type monolayers with anomalous Hall conductivity, magnetoresistance, and elastoresistance

Coupling multiferroic orders with emerging altermagnetism offers a promising route toward multifunctional quantum devices. Here, we combine symmetry analysis, systematic density functional theory screening, and nonequilibrium Green’s function calculations to investigate 48 NiAs-type (110) monolayers. We identify a class of ferroelastic-altermagnetic biferroics exhibiting intrinsic coupling between lattice strain and spin order. Specifically, metallic FeN and semiconducting MnTe monolayers emerge as representative systems, showing reversible ferroelastic switching with low barriers of 0.08 and 0.22 eV per formula unit and accessible signal intensity. FeN exhibits above-room-temperature (334 K) altermagnetism while MnTe possesses Néel temperature of 122 K. Both monolayers display ferroelastic-reversible momentum-dependent spin splitting (245 and 307 meV). This coupling enables tunable anomalous Hall conductivity and strain-controlled electronic transport. Prototype device-level simulations reveal magnetoresistance (454%), elastoresistance (155%), and high spin-filtering efficiency (-87%). These findings establish NiAs-type monolayers as a versatile platform for intrinsic biferroic coupling, providing a foundation for high-density, energy-efficient spintronic architectures.