Nanoengineering of an Si/MnGe quantum dot superlattice for high Curie-temperature ferromagnetism

Tianxiao Nie, Xufeng Kou, Jianshi Tang, Yabin Fan, Shengwei Lee, Qinglin He, Li Te Chang, Koichi Murata, Yin Gen, Kang L. Wang

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The realization and application of spintronic devices would be dramatically advanced if room-temperature ferromagnetism could be integrated into semiconductor nanostructures, especially when compatible with mature silicon technology. Herein, we report the observation of such a system-an Si/MnGe superlattice with quantum dots well aligned in the vertical direction successfully grown by molecular beam epitaxy. Such a unique system could take full advantage of the type-II energy band structure of the Si/Ge heterostructure, which could trap the holes inside MnGe QDs, significantly enhancing the hole-mediated ferromagnetism. Magnetic measurements indeed found that the superlattice structure exhibited a Curie temperature of above 400 K. Furthermore, zero-field cooling and field cooling curves could confirm the absence of ferromagnetic compounds, such as Ge8Mn11 (Tc ∼ 270 K) and Ge3Mn5 (Tc ∼ 296 K) in our system. Magnetotransport measurement revealed a clear magnetoresistance transition from negative to positive and a pronounced anomalous Hall effect. Such a unique Si/MnGe superlattice sets a new stage for strengthening ferromagnetism due to the enhanced hole-mediation by quantum confinement, which can be exploited for realizing the room-temperature Ge-based spin field-effect transistors in the future.

Original languageEnglish
Pages (from-to)3086-3094
Number of pages9
Issue number9
StatePublished - 7 Mar 2017


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