Multifunctionality of Magnetic La(Fe, Si/Al) ₁₃ ‐Based Materials: Negative Thermal Expansion and Magnetocaloric Effect

ABSTRACT In recent years, the field of magnetic materials has witnessed a paradigm shift from single‐function applications to multifunctional integration, driven by the growing demand for smart materials in advanced technologies. Among various magnetic systems, La(Fe, Si/Al) 13 ‐series materials have emerged as particularly promising candidates due to their extraordinary spin–lattice coupling effects. These materials exhibit remarkable negative thermal expansion (NTE) behavior and giant magnetocaloric effects (MCE) when subjected to a change in temperature and magnetic field, effectively addressing device cracking caused by the coefficient of thermal expansion mismatch and enabling efficient and eco‐friendly magnetic refrigeration, thereby demonstrating exceptional multifunctional properties. This comprehensive review focuses on La(Fe, Si/Al) 13 ‐based materials, systematically examining the influences of different structure‐stabilizing elements, chemical substitutions at La and Fe sites, and interstitial ion insertion on their crystal structure, electronic structure, and magnetic configuration. It further elucidates the critical role of spin–lattice coupling in the controllable regulation of magnetovolume effect (MVE) and MCE. The present review not only contributes to optimizing NTE and MCE in La(Fe, Si/Al) 13 ‐based materials but also provides theoretical guidance for developing novel multifunctional materials.