An investigation of phase transformation behavior in sputter-deposited PtMn thin films
An investigation of phase transformation behavior in sputter-deposited PtMn thin films
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DOI：
10.1007/s11837-006-0182-x
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发表时间：
2006
期刊：
影响因子：
2.6
通讯作者：
Chengxiang Ji;Peter F. Ladwig;R. Ott;Ying Yang;Joshua J. Yang;Y. Chang;E. Linville;Jenny Gao;B. Pant
中科院分区：
文献类型：
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作者：
Chengxiang Ji;Peter F. Ladwig;R. Ott;Ying Yang;Joshua J. Yang;Y. Chang;E. Linville;Jenny Gao;B. Pant
溅射沉积的等原子PtMn薄膜在巨磁阻自旋阀、隧道磁阻自旋阀和磁随机存取存储器中有广泛的应用。然而，发现沉积的薄膜是顺磁状态的无序A1相，而不是具有l10结构的反铁磁相，这是器件运行所必需的。因此，需要一个后退火步骤来诱导从沉积的A1面心立方相到反铁磁l10相的相变。用x射线衍射和差示扫描量热法研究了A1到l10的亚稳态转变。测定了原子的放热转化焓为−12.1 kJ/mol。利用Johnson-Mehl-Avrami分析模拟了转化动力学。
Sputter-deposited, equiatomic PtMn thin films have application in giant magnetoresistive spin valves, tunneling magnetoresistive spin valves, and magnetic random access memory. However, the as-deposited films are found to be a disordered A1 phase in a paramagnetic state rather than an antiferromagnetic phase with L10structure, which is needed for device operation. Therefore, a postannealing step is required to induce the phase transformation from the asdeposited A1 face-centered-cubic phase to the antiferromagnetic L10phase. The A1 to L10metastable transformation was studied by x-ray diffraction and differential-scanning calorimetry. An exothermic transformation enthalpy of −12.1 kJ/mol of atoms was determined. The transformation kinetics were simulated using the Johnson-Mehl-Avrami analysis.