Room temperature X-ray diffraction patterns of Ni50− x Cu x Mn38Sn12 alloys with x = 0, 2, 4, 6. The crystal structures of Ni50Mn38Sn12 and Ni48Cu2Mn38Sn12 are 10 M modulated martensitic structures with an orthorhombic unit cell. The crystal structure of Ni44Cu6Mn38Sn12 is L21. The pattern of Ni46Cu4Mn38Sn12 contains two sets of diffraction peaks indicating that both the martensitic and austenitic phase coexistence in Ni46Cu4Mn38Sn12. The L21 structure with four interpenetrating fcc sublattices, denoted as A, B, C, and D, respectively, is shown in the top right corner.
The M-T curves under 0.05 T of Ni50− x Cu x Mn38Sn12 alloys (x = 0, 2, 4, 6) in ZFC, FCW, and FCC sequences. Curie temperature (TC ) is determined from the minimum of dM-dT curves. The inset figure is an expanded view of martensitic transformation region for Ni50Mn38Sn12.
Magnetization hysteresis loops of Ni46Cu4Mn38Sn12 alloy measured at low temperatures of 10 K, 30 K, and 60 K, respectively. Prior to each loop measurement, the sample were prepared in field cooling of 1 T.
The temperature dependence of the resistance of Ni50− x Cu x Mn38Sn12 alloys (x = 2, 4, 6) measured under 0 and 5 T in the temperature range from 200 K to 340 K.
Magnetoresistance as a function of temperature measured at 5 T for Ni50− x Cu x Mn38Sn12 alloys (x = 2, 4, 6) during heating process.
Magnetoresistance as a function of field strength measured at various temperatures for Ni46Cu4Mn38Sn12. Prior to each curve measurements, the sample was first cooled in zero field to 200 K to obtain a complete martensitic state and then heated to the measuring temperature.
Crystal structures and lattice parameters of Ni50− x Cu x Mn38Sn12 alloys measured at room temperature. There are two phases coexisting in Ni46Cu4Mn38Sn12.
The characteristic temperatures of Ni50 − x Cu x Mn38Sn12 alloys (x = 0, 2, 4, 6) denoted as TC A , TC M , and MS , respectively. e/a is the valence electron concentration per atom determined as the concentration-weighted average of the valence electrons. The magnetic properties of austenitic phase and martensitic phase in the vicinity of martensitic transformation region are also listed in this table. ΔT is the shift of martensitic transformation temperature under 5 T.
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