Lattice dynamics of Ni–Mn–Al Heusler alloys

✍ Scribed by X. Moya; Ll. Mañosa; A. Planes; T. Krenke; M. Acet; E.F. Wassermann; M. Morin; V.O. Garlea; T.A. Lograsso; J.L. Zarestky

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 140 KB
• Volume: 481-482
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/j.msea.2006.12.217

✦ Synopsis

We have studied the lattice dynamics of a Ni 54 Mn 23 Al 23 (at.%) Heusler single-crystalline alloy by means of neutron scattering and ultrasonic techniques. Results show the existence of a number of precursor phenomena. We have found an anomaly (dip) in the low TA 2 phonon branch at the wave number ξ 0 ≈ 0.33 (in reciprocal lattice units) that becomes more pronounced (phonon softening) with decreasing temperature. We have also observed softening of the associated shear elastic constant (C ) with decreasing temperature. Ultrasonic measurements under applied magnetic field, both isothermally and varying the temperature show that the values of elastic constants depend on magnetic order thus evidencing magnetoelastic coupling.