| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Neutron and X-ray Scattering in Materials Science and Engineering
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| Presentation Title |
The Role of Vibrational Entropy Across Magnetostructural Transition in Heusler Alloys |
| Author(s) |
Saqeeb Adnan, Ibrahim Karaman, Daniel Salas Mula, Raymundo Arroyave, Raphael Hermann, Douglas Abernathy, Michael Manley |
| On-Site Speaker (Planned) |
Saqeeb Adnan |
| Abstract Scope |
The all-d-metal Ni-(Co)-Mn-Ti-based Heusler alloys exhibit a giant magnetocaloric effect at near-room temperatures, making them promising candidates for solid-state magnetic refrigeration. This large caloric effect is connected to a first-order magnetostructural martensitic transformation where strong phonon-magnon coupling persists and is further enhanced by the d-d covalent hybridization. However, the crucial details of the transition entropy and the contributions from its constituent sources (i.e., magnetic, lattice & electronic)remain unclear. In this study, we perform time-of-flight inelastic neutron scattering measurements on Ni36.5Co13.5Mn35Ti15 single and polycrystalline alloys across the transition temperatures. The measured phonon density of states indicates the lattice contribution towards entropy change to be as high as ~22J/Kg/K. We also find that the magnetic scattering present below the martensitic transition temperature is very weak, and it shows no long-range ordering, consistent with a spin-glass state. Our findings will provide critical insight toward an accurate assessment of underlying phases and transition entropy. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Magnetic Materials, Phase Transformations, |