[14a-A501-1~13] 10.2 Fundamental and exploratory device technologies for spin

▼ [14a-A501-8] Spin-relaxation mechanism in Cu/Bi systems investigated by weak anti-localization

〇(B)Masaki Abe¹, Hiromu Gamou¹, Shutaro Karube^1,2, Makoto Kohda^1,2,3, Junsaku Nitta^1,2,3 (1.Tohoku Univ. Eng., 2.Tohoku Univ. CSRN, 3.Tohoku Univ. CSIS)

Keywords:spin relaxation, Rashba effect, weak anti-localization

The Rashba-Edelstein effect (REE) is known as the alternative way to generate spin current in addition to the bulk spin Hall effect (SHE). A Cu/Bi interface is expected to generate spin current due to the strong REE. It is often difficult to separate the REE and the SHE by using heavy metal/ferromagnet bi-layer systems. In this study, we have investigated the spin-relaxation mechanism of Cu/Bi system by utilizing weak antilocalization (WAL) analysis which does not require any ferromagnet layer. Cu (0.6-8 nm)/Bi (2, 3, 5 nm)/AlO_x (2 nm) thin films were sputtered on sapphire (0001) substrates. Magneto-conductance and Hall resistance measurements were perfomed in a ⁴He cryostat at 2 K. From the results of the magneto-conductance measurement, it is found that all Cu/Bi samples show WAL. Analytical results revealed that the spin relaxation time is inversely proportional to the momentum scattering time. It means that the D'yakonov-Perel mechanism is dominant over the Elliot-Yafet mechanism. This result indicates that the REE is important at the Cu/Bi interface.