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Magnetoresistance in ferromagnetic shape memory alloy NiMnFeGa |
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| Authors: | Z.H. LiuX.Q. Ma Z.Y. ZhuH.Z. Luo G.D. LiuJ.L. Chen G.H. Wu Xiaokai ZhangJohn Q. Xiao |
| Affiliation: | a Department of Physics, University of Science and Technology Beijing, Beijing 100083, China b Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China c Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA |
| Abstract: | The magnetoresistance (MR){=[R(H)−R(0)]/R(0)} properties in ferromagnetic shape memory alloy of NiMnFeGa ribbons and single crystals, and NiFeGa ribbons have been investigated. It is found that the NiMnFeGa melt-spun ribbon exhibited GMR effect, arising from the spin-dependent scattering from magnetic inhomogeneities consisting of antiferromagnetically coupled Mn atoms in B2 structure. In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8TC, regardless of sample structures. This may be explained by the s-d model. At low temperatures, conventional AMR behaviors due to the spin-orbital coupling are observed. This is most likely due to the diminished MR from s-d model because of much less spin fluctuation, and is not associated with martensite phase. MR anomaly at intermediate field (ρ⊥>ρ||) is also observed in single crystal samples, which may be related to unique features of Heusler alloys. |
| Keywords: | Magnetoresistance Heusler alloys Ferromagnetic shape memory alloys |
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