magnetostructural

Magnetostructural refers to the class of materials and phenomena in which magnetic order and crystal structure are intimately linked, such that changes in magnetic state are accompanied by structural distortions or phase transitions. This coupling between spin and lattice, often called spin-lattice or magnetoelastic coupling, can produce first-order transitions with noticeable changes in symmetry, shape, or volume. Magnetostructural effects are central to phenomena such as the magnetocaloric effect and magnetic shape memory.

The underlying mechanism involves the dependence of magnetic exchange interactions on interatomic distances and angles, along with the lattice’s ability to respond to magnetic free-energy changes. In many systems, the exchange energy is minimized by a particular structure; when magnetic order changes, the lattice may restructure to accommodate a new magnetic ground state. This interplay can lead to large entropy changes, pronounced hysteresis, and temperature- or field-tunable transitions.

Prominent materials classes exhibiting magnetostructural coupling include FeRh, which undergoes a metamagnetic transition near room temperature with a concurrent lattice change, and Mn-based antiperovskites like Mn3GaN, noted for strong spin-lattice interactions. Magnetic shape memory alloys (for example, Ni-Mn-Ga) demonstrate large strains driven by magnetic-field-induced reorientation of martensitic variants. Heusler and related compounds also show related coupling, enabling tunable transition temperatures and functional responses.

Applications span solid-state cooling, actuators, and sensors, while research emphasizes designing materials with controllable magnetostructural transitions for energy-efficient technologies and a deeper understanding of spin–lattice physics.