Phonon anomaly, central peak, and microstructures in Ni2MnGa.
Phonon anomaly, central peak, and microstructures in Ni2MnGa.
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DOI：
10.1103/physrevb.51.11310
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发表时间：
1995-05
期刊：
影响因子：
--
通讯作者：
Zheludev;Shapiro;Wochner;Schwartz;Wall;Tanner
中科院分区：
文献类型：
--
作者：
Zheludev;Shapiro;Wochner;Schwartz;Wall;Tanner
用非弹性中子散射和透射电子显微镜研究了Ni2MnGa形状记忆铁磁Heusler合金单晶在T_M= 220K的马氏体相变以上的宽温区。在波矢为0.33的情况下，[λ 0] TA 2声子分支中出现了明显的软化现象，尽管不完全.色散曲线中的异常被示出为在高温下持续存在，甚至高于居里点。在弹性漫散射中的温度依赖性峰也存在于相同的波矢量λ 0处，其发展成代表高温Heusler和低温马氏体结构之间的中间相的布拉格峰。
Inelastic neutron scattering and transmission electron microscopy have been used to study a single crystal of the Ni 2 MnGa shape-memory ferromagnetic Heusler alloy in a wide temperature range above the martensitic phase transformation at T M= 220 K. Significant, though incomplete, softening in the [ζζ0] TA 2 phonon branch has been observed at a wave vector ζ 0≊ 0.33. The anomaly in the dispersion curve is shown to persist at high temperature, even above the Curie point. A temperature-dependent peak in the elastic diffuse scattering is also present at the same wave vector ζ 0, which develops into a Bragg peak representative of an intermediate phase between the high-temperature Heusler and the low-temperature martensitic structures.