Martensitic transformation in Ni-rich Ni55Mn25In20 Heusler alloy: Experiment and first-principles calculations

• Ni55Mn25In20 ribbons with ordered L21 structure were prepared.
• A martensitic transformation has been observed in Ni55Mn25In20.
• A large MR up to 17% is observed.
• The cubic structure becomes unstable by partial substitution of In with Ni.
• The driving force of the martensitic transformation is discussed.

A martensitic transformation has been observed in Ni-rich Ni55Mn25In20 Heusler alloy and been theoretically investigated by first-principles calculations. The samples are prepared by the melt-spun method and the ribbons show an ordered L21 structure at room temperature. Magnetization and electrical resistance measurements show that a martensitic transformation occurs at about 156 K, with both phases exhibiting ferromagnetic ordering. A negative magnetoresistance of 17% is observed at a magnetic field of 50 kOe due to the magnetic field induced reverse martensitic transformation. Electronic structure calculations indicate that the 3d states of Ni occupied in In site strongly hybridize with the Ni: 3d states. Such hybridization plays an important role in driving the martensitic transformation.