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At least 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Lattice Vibrations Boost Demagnetization Entropy in Shape Memory Alloy

Magnetocaloric (MC) materials present an avenue for chemical-free, solid state refrigeration through cooling via adiabatic demagnetization. We have used inelastic neutron scattering to measure the lattice dynamics in the MC material Ni 45 Co 5 Mn 36.6 In 13.4 . Upon heating across TC, the material exhibits an anomalous increase in phonon entropy of 0.17 0.04 k_B/atom, which is nine times larger than expected from conventional thermal expansion. We find that the phonon softening is focused in a transverse optic phonon, and we present the results of first-principle calculations which predict a strong coupling between lattice distortions and magnetic excitations.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on ARCS at 300 K and 450 K

These sqw files were generated by combining all of the individual crystal angles scans using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html). The neutron incident energy for both temperatures was 50 meV. The file labeled 50meV_450K_All.sqw is the 450 K data and the file labeled 50meV_RT_All.sqw is for the 300 K data. The crystal was oriented such that HHL is in the scattering plane.

excitations↗
DOE OSTI2024

Strain glass state of magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on ARCS at 300 K

Combined inelastic neutron scattering data from ARCS on the strain glass state of Ni45Co5Mn36.6In13.4 measured at 300 K. Crystal was oriented with HHL in the scattering plane. To obtain a large Q-E volume the crystal was rotated in the beam and the individual angles were combined using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html).

excitations↗
DOE OSTI2024

Strain glass state of magnetic shape memory alloy Ni45Co5Mn36.6In13.4 measured on SEQUOIA at 5 K

Combined inelastic neutron scattering data from SEQUOIA on the strain glass state of Ni45Co5Mn36.6In13.4 measured at 5 K. Crystal was oriented with HHL in the scattering plane. To obtain a large Q-E volume the crystal was rotated in the beam and the individual angles were combined using the HORACE software package (https://pace-neutrons.github.io/Horace/unstable/user_guide/Getting_started.html).

excitations↗