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Issue 9, 2017
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Nanoengineering of an Si/MnGe quantum dot superlattice for high Curie-temperature ferromagnetism

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Abstract

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.

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

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Article information


Submitted
07 Nov 2016
Accepted
21 Jan 2017
First published
23 Jan 2017

Nanoscale, 2017,9, 3086-3094
Article type
Paper

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

T. Nie, X. Kou, J. Tang, Y. Fan, S. Lee, Q. He, L. Chang, K. Murata, Y. Gen and K. L. Wang, Nanoscale, 2017, 9, 3086
DOI: 10.1039/C6NR08688H

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