Clarification of origin of the giant-magnetoresistance associated to magnetic field-induced structural transformation in Ni-based Heusler alloys

2015 Fiscal Year Final Research Report

• Project/Area Number: 25289217
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Physical properties of metals/Metal-base materials
• Research Institution: Tohoku University
• Principal Investigator: Umetsu Rie 東北大学, 金属材料研究所, 准教授 (60422086)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 電子・磁気物性 / 構造相変態 / 巨大磁気抵抗効果 / 電子状態 / 磁気モーメント

Outline of Final Research Achievements

Off-stoichiometric NiMn-based Heusler alloys indicate martensitic transformation from ferromagnetic parent phase to weak-(or non-)magnetic martensite phase under cooing. At the transformation, structural change and magnetic transition occur at the same time. Therefore, drastic change of the magnetization happens and applying a magnetic field induces inverse martensitic transformation. Unique phenomena, that is, giant magnetoresistance, superelasticity, magnetocaloric effect are also observed associated with the martensitic transformation. Such drastic changes of the various physical properties are considered to be due to the change of the electronic states between in the parent phase and in the martensite phase. In the present study, specimens of three kinds of alloy systems were fabricated in wide concentration region, and electronic specific heat coefficient and the Debye temperature were confirmed by low-temperature specific heat measurements.

Free Research Field

金属物性