Charge-spin interconversion using large Spin Orbit (SO) material has been intensively studies thanks to potential spintronic application in information and communication technology. It has been demonstrated that the interface between heavy metal and both metallic and insulating ferromagnetic layers could lead to spin current absorption and manipulation of the magnetization driven by electrical pulse[1][2]. More recently Rashba surface states and Topological insulator (TI) have been reported like a good candidate for the spin to charge interconversion[3]. Nevertheless, current shunting by metallic ferromagnet at the interface with TI makes hard to address unambiguously the charge to spin conversion from surface states. As a supplementary effect, the role of proximity effect and exchange interaction in between ferromagnetic material and TI needs to be clarified. To comprehend this issue, we first grow a thin film of magnetic insulator Tm3Fe5O12(TmIG) by off-axis sputtering and demonstrated the high quality of the film in the thickness range of 5 to 15 nm (Figure. 1(a)). We achieved to demonstrate, as a reference experiment, spin current absorption at the interface in between Pt and TmIG by 2nd harmonic experiment to extract torque and magnetization reversal driven by pulse current experiment. The high quality of the film makes possible to growth by MBE Bi2Se3 TI on top of it as illustrated in Figure 1(b). The TmIG films exhibit perpendicular magnetic anisotropy (Figure 1 (c)) with nearly bulk magnetization. We will address a comparative study of the interfacial effect when using SHE material (Pt) or TI (Bi2Se3) with ferromagnetic insulator TmIG. This work has been supported by the Defense Advanced Research ProjectsAgency (DARPA) Topological Excitations in Electronics (TEE) program, through Grant MIPR No. HR0011831554.

![](https://assets.underline.io/uploads/markdown_image/1/image/d2384c7e071cf59f2e36c9d864aa2f2a.jpg)

Figure 1 (a) X-Ray (θ-2θ) diffraction patterns recorded on TmIG(5-15nm) thin films grown on GGG substrate. (b) RHEED patterns recorded before (on TmIG surface) and after Bi2Se3 growth. (c) Magnetization hysteresis recorded in out-of-plane field on TmIG(15nm) sample.

Sajid Husain

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