Development of the artificial design technique of the energy dependence of the spin polarization

2016 Fiscal Year Final Research Report

• Project/Area Number: 26630123
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Electronic materials/Electric materials
• Research Institution: The University of Tokyo
• Principal Investigator: Ohya Shinobu 東京大学, 大学院工学系研究科(工学部), 准教授 (20401143)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: スピントロニクス / 分子線エピタキシー / 量子効果 / ヘテロ構造

Outline of Final Research Achievements

Using ferromagnetic-semiconductor quantum heterostructures, which are an ideal model system of a ferromagnetic quantum heterostructure, we have shown that the quantum size effect is strengthened by the ferromagnetic transition of the quantum well and that magnetic anisotropy is changed by the quantum size effect. We have demonstrated epitaxial single-crystal growth of Fe/MgO on a semiconductor Ge and a ferromagnetic GeFe, which is a ferromagnetic semiconductor based on Ge, and we have successfully observed tunneling magnetoresistance (TMR) in these structures for the first time. High TMR ratios up to 200% were observed in Fe/MgO/Fe/MgO/Ge, which contains an Fe quantum well. We observed a systematic change in the I-V characteristics when varying the thickness of the Fe quantum well. This is the first observation of the quantum size effect in the Fe quantum well grown on Ge.

Free Research Field

電子工学