Lateral spin-valve devices on germanium on insulator

For the first step of Ge-based spintronic devices compatible with electronic–photonic integration circuits on Si, we experimentally demonstrate one of the spintronic devices on germanium on insulator (GOI) substrates. By optimizing fabrication conditions for GOI(111) substrate, a Ge-based spin transport layer, and a heavily doped Ge layer, we obtain an epitaxial ferromagnetic Co-based Heusler-alloy film on the GOI structure. For demonstrating electrical spin injection and detection, lateral spin-valve devices are fabricated on the GOI substrate, and then, spin transport from 8 K to room temperature is observed. This work will open a path for Ge-based spintronic devices compatible with electronic–photonic integration circuits on Si.