Comparison of spin lifetimes in n-Ge characterized between three-terminal and four-terminal nonlocal Hanle measurements

We compared the temperature dependence of spin lifetime in n-Ge characterized from three-terminal (3T) and four-terminal (4T) Hanle measurements using single-crystalline Fe/MgO/n-Ge tunnel junctions. The bias conditions of the two schemes were chosen to be about the same in order to compare the spin lifetimes (τ3T and τ4T). The temperature dependences of τ3T and τ4T behave in a very similar way at the low temperature region (T ≤ 10 K), and both τ3T and τ4T decrease as the temperature increases, which is consistent with the dominating Elliot–Yafet spin relaxation mechanism in bulk Ge. However, when the temperature is higher than 10 K, τ4T is longer than τ3T, which may be explained by the fact that 3T Hanle measurements are more easily affected by additional scattering effects caused by the accompanied charge current and electric field in the 3T geometry. (paper)