All-epitaxial Co_2FeSi/Ge/Co_2FeSi trilayers fabricated by Sn-induced low-temperature epitaxy

摘要

We demonstrate low-temperature growth of all-epitaxial Co_2FeSi/Ge/Co_2FeSi trilayer structures by developing Sn-induced surfactant-mediated molecular beam epitaxy (SMBE) of Ge on Co_2FeSi. Despite the growth of a semiconductor on a metal, we verify that the inserted Sn monolayers between Ge and Co_2FeSi enable to promote the 2D epitaxial growth of Ge up to 5 nm at a T_G of 250 ℃. An understanding of the mechanism of the Sn-induced SMBE leads to the achievement of all-epitaxial Co_2FeSi/Ge/Co_2FeSi trilayer structures with spin-valve-like magnetization reversals. This study will open a way for vertical-type and high-performance Ge-based spintronics devices.