Superlattice of Fe x Ge 1−x nanodots and nanolayers for spintronics application

Fe x Ge 1−x superlattices with two types of nanostructures, i.e. nanodots and nanolayers, were successfully fabricated using low-temperature molecular beam epitaxy. Transmission electron microscopy (TEM) characterization clearly shows that both the Fe x Ge 1−x nanodots and nanolayers exhibit a lattice-coherent structure with the surrounding Ge matrix without any metallic precipitations or secondary phases. The magnetic measurement reveals the nature of superparamagnetism in Fe x Ge 1−x nanodots, while showing the absence of superparamagnetism in Fe x Ge 1−x nanolayers. Magnetotransport measurements show distinct magnetoresistance (MR) behavior, i.e. a negative to positive MR transition in Fe x Ge 1−x nanodots and only positive MR in nanolayers, which could be due to a competition between the orbital MR and spin-dependent scatterings. Our results open a new growth strategy for engineerin...

Tianxiao Nie, Xufeng Kou, Jianshi Tang, Yabin Fan, Murong Lang, Li-Te Chang, Chia-Pu Chu, Liang He, Sheng-Wei Lee, Faxian Xiu, Jin Zou and Kang L Wang

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