Room Temperature Ferromagnetic Mn:Ge(001).
Room Temperature Ferromagnetic Mn:Ge(001).
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DOI：
10.3390/ma7010106
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发表时间：
2013-12-27
期刊：
影响因子：
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通讯作者：
Teodorescu CM
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文献类型：
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作者：
Lungu GA;Stoflea LE;Tanase LC;Bucur IC;Răduţoiu N;Vasiliu F;Mercioniu I;Kuncser V;Teodorescu CM
我们报道了通过在 Ge(001) 上简单沉积锰而获得的室温铁磁 Mn-Ge 系统的合成，并在相对较高的温度（从 250 °C 开始）下加热。通过低能电子衍射（LEED）、扫描隧道显微镜（STM）、高分辨率透射电子显微镜（HRTEM）、X射线光电子能谱（XPS）、超导量子干涉装置（SQUID）和磁光克尔效应（MOKE）对样品进行了表征。在相对较高的温度 (350 °C) 下沉积的样品通过 HRTEM 显示形成了约 5–8 nm 直径的 Mn5Ge3 和 Mn11Ge8 团聚物，而 XPS 识别出至少两个含锰相：团聚物以及富含 Ge 的 MnGe~2.5 相，或稀释到 Ge(001) 晶体中的锰。 LEED 揭示了在单晶基底上沉积相对大量的 Mn (100 nm) 后长程有序的持久性。 STM 探测了表面上二聚体行的存在，与 Ge(001) 上的 Ge-Ge 二聚体相比，这些二聚体行稍微拉长。这些薄膜在室温下表现出明显的铁磁性，开启了在几乎理想终止的Ge表面后面形成磁性相的可能性，这可以在半导体基底上的磁性功能集成中找到应用。 SQUID 探测了超顺磁性相的共存，其中一个相可能归因于稀释的磁性半导体。提出并讨论了室温铁磁相可能是锰稀释到 Ge 晶体中的假设。
We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001), heated at relatively high temperature (starting with 250 °C). The samples were characterized by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID), and magneto-optical Kerr effect (MOKE). Samples deposited at relatively elevated temperature (350 °C) exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001) crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm) deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001). The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.