The Giant Inverse Spin Hall Effect in Semiconductor Alloy/Ferromagnetic Insulator (Ge1–xBix/YIG) Spin Heterojunction

An n-type semiconductor Ge1–xBix (x = 11.6–22.7%) alloy film is, for the first time, regulated to grow into a GeBi/yttrium iron garnet (YIG) spin heterojunction with a ferromagnetic insulator Y3Fe5O12 garnet film wafer; tests found that regulating the Bi ions content and enhancing spin–orbit torque (SOT) of the spin heterojunction can control signal voltage amplitude, bandwidth, and waveform of the inverse spin Hall effect (ISHE). The Bi doping can not only change the electron concentration of the GeBi semiconductor film and mixing conductance of the GeBi/YIG bilayer but also increase the SOT between GeBi film and YIG film, driving the domain superfast reversal and enhancing the ISHE. Moreover, part of the Bi doping affects the magnetic moments distribution of the spin heterojunction and ferromagnetic resonance absorption. Our research shows the possibility that the Ge1–xBix/YIG (x = 11.6–22.7%) spin heterojunction is one of the best for spin wave devices in the future.