We investigated spin-to-charge conversion in sputtered Bi43Se57/Co20Fe60B20 heterostructures with in-plane magnetization at room temperature. High spin-to-charge conversion voltage signals have been observed at room temperature. The transmission electron microscope images show that the sputtered bismuth selenide thin films are nanogranular in structure. The spin-pumping voltage decreases with an increase in the size of the grains. The inverse Edelstein effect length (λIEE) is estimated to be as large as 0.32 nm. The large λIEE is due to the spin-momentum locking and is further enhanced by quantum confinement in the nanosized grains of the sputtered bismuth selenide films. We also investigated the effect on spin-pumping voltage due to the insertion of layers of MgO and Ag. The MgO insertion layer has almost completely suppressed the spin-pumping voltage, whereas the Ag insertion layer has enhanced the λIEE by 43%.
Bibliographical noteFunding Information:
This work was supported in part by ASCENT, one of six centers in JUMP, a Semiconductor Research Corporation (SRC) program sponsored by DARPA. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under award number ECCS-1542202.
- granular bismuth selenide
- inverse Edelstein effect
- quantum confinement effect
- spin-to-charge conversion
- topological insulator