Mössbauer spectroscopy study on the magnetic transition in Mn1.1Fe0.9P0.8Ge0.2
Mössbauer spectroscopy study on the magnetic transition in Mn1.1Fe0.9P0.8Ge0.2
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DOI：
10.1063/1.3067496
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发表时间：
2009-02
影响因子：
3.2
通讯作者：
X. B. Liu;Z. Altounian;D. Ryan;M. Yue;Zhiqiang Li;Danmin Liu;Jiuxing Zhang
中科院分区：
文献类型：
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作者：
X. B. Liu;Z. Altounian;D. Ryan;M. Yue;Zhiqiang Li;Danmin Liu;Jiuxing Zhang
用磁性测量和F_（57）e穆斯堡尔谱研究了Mn_（1.1）Fe_（0.9）P_（0.8）Ge_（0.2）的磁转变。合金为六方Fe_2 P型结构，晶格常数a=6.0476（4）A，c=3.4766（7）A。体磁化强度测量和穆斯堡尔谱都表明，所制备的样品在第一次冷却时的转变温度（TC 1 ≈200 K）明显低于热循环至20 K后的转变温度（TC 20 K=240 K）。在第一次冷却/加热循环后，材料的行为稳定，并且在TC中没有观察到进一步的变化。通过对稳定样品的研究，我们发现超精细场Bhf（T）的温度依赖性比简单的平均场布里渊函数预测的更快，并且Bhf（T）在冷却与加热时表现出10 K的热滞后.这些结果表明，TC处的磁转变是一级的，并提示存在一个附加的不可逆磁结构。
The magnetic transition has been studied in Mn1.1Fe0.9P0.8Ge0.2 by magnetic measurements and F57e Mossbauer spectroscopy. The alloy crystallizes in the hexagonal Fe2P-type structure with lattice constants of a=6.0476(4) A and c=3.4766(7) A. Both bulk magnetization measurements and Mossbauer spectroscopy show that the as-prepared sample has a significantly lower transition temperature on first cooling (TC1≈200 K) than after it has undergone thermal cycling to 20 K (TC20 K=240 K). The behavior of the material stabilizes after the first cooling/heating cycle and no further changes are observed in TC. Working with a stabilized sample, we find that the temperature dependence of the hyperfine field, Bhf(T), is more rapid than that predicted by a simple mean field Brillouin function, and in addition, Bhf(T) shows a thermal hysteresis of 10 K upon cooling versus heating. These results show that the magnetic transition at TC is definitely first order and suggest that there is an additional irreversible magnetostru...