In-situ Neutron Scattering Study to Understand the Magnetoelastic Coupling in Magnetic Shape Memory Alloys

Smart materials which provide rapid responses to mechanical and magnetic stimuli hold the promise for future generations of sensors and actuators. Magnetic shape memory (MSM) alloys which exhibit such responses can transform a wide spectrum of transducer technologies in diversified fields such as aerospace, automotive, underwater navigation, biomedical, surveillance and consumer electronics. Compositional and microstructural design of MSM alloys with desired magneto-mechanical responses hinges on having a fundamental understanding of the strong magnetoelastic coupling in this class of materials. We propose an experimental study to determine the nature of magnetoelastic coupling in MSM alloys. The experimental approach will be based on in-situ neutron scattering experiments under a combined magnetic field and mechanical load, complemented by real space imaging with spin-polarized scanning electron microscopy. The approach will be applied to a prototypical Ni-Mn-Ga single crystal alloy, where the combined effects of stress and magnetic field on the structural stability and magnetoelastic behavior will be investigated. The proposed study will elucidate physical insights underlying the strong magnetoelastic coupling in MSM alloys, thereby providing guidance in the design of new materials for sensor and actuator applications. Experimental characterization of magnetoelastic coupling will also provide a benchmark for testing predictions by first-principles calculations or phenomenological theories in MSM alloys.