Electrical Detection of Spin Accumulation and Relaxation in P-Type Germanium

We report on electrical measurements of spin-dependent transport of holes in all-epitaxial CoFe/p-type germanium (p-Ge)/Fe3Si spin valves, where the hole concentration (p(h)) of the p-Ge layer is estimated to be similar to 10(18) cm(-3). Spin-accumulation output voltages can electrically be detected in the antiparallel magnetization state between CoFe and Fe3Si ferromagnetic electrodes. The room-temperature spin lifetime of holes in the p-Ge layers can tentatively be discussed in terms of the theory by Fert and Jaffres. We propose that the use of (111)-oriented p-Ge with a hole concentration of similar to 10(18) cm(-3) enables the transport of spin-polarized holes in bulk Ge even at room temperature.