W. Ito, R. Y. Umetsu, K. Ito, K. Koyama, A. Fujita, K. Watanabe, R. Kainuma, K. Ishida, Tohoku University, Sendai, Japan
Recently, we reported that in the NiMnIn and NiMnSn based Heusler alloys, an unusual martensitic transformation from the ferromagnetic parent phase to the antiferromagnetic-like martensite phase occurs and magnetic field induced reverse martensitic transformation (MFIRT) is obtained in a magnetic field. In the present study, the martensitic transformation, magnetic and electrical resistivity (ER) properties under a large external magnetic field in the Ni45Co5Mn36.7In13.3 meta-magnetic shape memory alloy were investigated by extraction-type magnetometer with superconducting magnet, superconducting quantum interference device (SQUID) and conventional four-probe method. A drastic change of ER due to martensitic transformation was observed in the vicinity of 280 K under 0.05 T, 250 K under 3 T and 210 K under 5 T, which is consistent with the large magnetization change. The ER change under 0.05 T was extremely large over about 80 % ( = [r(200 K)-r(270 K)]/r(200 K)). A giant magnetoresistance (GMR) effect of about -80~90% was also confirmed accompanying the MFIRT. On the other hand, it was observed that the martensitic transformation always stops in the vicinity of 150 K even during the transformation, and that magnetic hysteresis, which was determined by magnetization and ER changes due to the large magnetic field, drastically increases with decreasing test temperature.
Summary: Recently, we reported that in the NiMnIn and NiMnSn based Heusler alloys, an unusual martensitic transformation from the ferromagnetic parent phase to the antiferromagnetic-like martensite phase occurs and magnetic field induced reverse martensitic transformation (MFIRT) is obtained in a magnetic field. In the present study, the martensitic transformation, magnetic and electrical resistivity (ER) properties under a large external magnetic field in the Ni45Co5Mn36.7In13.3 meta-magnetic shape memory alloy were investigated by extraction-type magnetometer with superconducting magnet, superconducting quantum interference device (SQUID) and conventional four-probe method. A drastic change of ER due to martensitic transformation was observed in the vicinity of 280 K under 0.05 T, 250 K under 3 T and 210 K under 5 T, which is consistent with the large magnetization change. The ER change under 0.05 T was extremely large over about 80 % ( = [ĉ(200 K)-ĉ(270 K)]/ĉ(200 K)). A giant magnetoresistance (GMR) effect of about -80~90% was also confirmed accompanying the MFIRT. On the other hand, it was observed that the martensitic transformation always stops in the vicinity of 150 K even during the transformation, and that magnetic hysteresis, which was determined by magnetization and ER changes due to the large magnetic field, drastically increases with decreasing test temperature.
