Electrical spin injection to Germanium using a single crystalline Fe/MgO/Ge tunneling junction

Germanium has long been predicted a superior candidate for spintronics with enhanced spin lifetime and transport length due to low spin--orbit interaction and lattice inversion symmetry. One of the critical challenges, however, is to electrically create spin accumulation in otherwise non-magnetic Ge. In this work, we report electrical spin injection to bulk n-type Ge using a single crystalline Fe/MgO/Ge tunneling junction. The spin lifetime and diffusion length are extracted from both 3-terminal Hanle measurement and non-local spin valve measurement. The spin relaxation mechanism in n-type Ge has also been explicitly analyzed from the bias and temperature dependence of the spin relaxation rate.