Material and Spin Transport Characterization in Gd-alloyed Bismuth Selenide*

Spin Hall systems have garnered a significant amount of attention recently because of their applications in spintronics. Spin logic devices require a higher resistivity for CMOS integration and cascading. One such example is magneto-electric spin-orbit device, which requires a resistivity > 10 mOhm.cm. Furthermore, scaling of the materials require a homogeneity. We developed a homogenous amorphous material, Gd (40%)-alloyed Bi_xSe_1-x (60%), which shows a resistivity of 60 mOhm.cm. TEM shows a uniform distribution of Gd throughout the Bismuth Selenide layer. The temperature dependent resistivity shows 3D Mott hopping which persists till room temperature. We performed second harmonic characterization on BSG (6,8,12,16nm)/CFB(5nm) films. The second harmonic signal shows a strong thermal voltage generated from Joule heating of the interface. We performed spin pumping on the BSG(6)/CFB(5) which shows resonance. Spin Hall efficiency and inverse Edelstein length show frequency dependence. This frequency dependence suggests that the spin-to-charge conversion in the material is affected by the presence of magnetic moments in the material.