Local atomic arrangement and martensitic transformation in Ni$_{50}$Mn$_{35}$In$_{15}$: An EXAFS Study

TL;DR

This study uses EXAFS to investigate local atomic arrangements in Ni50Mn35In15, revealing structural changes during martensitic transformation that influence its magnetic and mechanical properties.

Contribution

It provides new insights into local atomic arrangements and bond length changes during phase transformation in Ni-Mn-In alloys using EXAFS.

Findings

Local structural changes occur during martensitic transformation

Bond length variations indicate hybridization effects

Insights into atomic-level mechanisms driving phase change

Abstract

Heusler alloys that undergo martensitic transformation in ferromagnetic state are of increasing scientific and technological interest. These alloys show large magnetic field induced strains upon martensitic phase change thus making it a potential candidate for magneto-mechanical actuation. The crystal structure of martensite is an important factor that affects both the magnetic anisotropy and mechanical properties of such materials. Moreover, the local chemical arrangement of constituent atoms is vital in determining the overall physical properties. Ni$_{50}$Mn$_{35}$In$_{15}$ is one such ferromagnetic shape memory alloy that displays exotic properties like large magnetoresistance at moderate field values. In this work, we present the extended x-ray absorption fine-structure measurements (EXAFS) on the bulk Ni$_{50}$Mn$_{35}$In$_{15}$ which reveal the local structural change that occurs upon phase transformation. The change in the bond lengths between different atomic species helps in understanding the type of hybridization which is an important factor in driving such Ni-Mn based systems towards martensitic transformation.