Structural, interface, and device properties of some Bi2Se3-based spintronic heterostructures.

Incorporating Topological Insulators in spintronic heterostructures and devices have gained interest due to several recent observations of greater spin-orbit torque compared to heavy metals. However, strong tunnel magnetoresistance (TMR) behavior has not been established with TIs compared to standard spintronics interfaces such as CoFeB-MgO. In this work, we have systematically investigated the structural, interface properties of prototypical a TI material (Bi2Se3) with normal Ferromagnets such as Co. Bilayer (Bi2Se3/Co) and TMR heterostructures (Co/Bi2Se3/Co) was fabricated using magnetron sputtering and their structure and interface investigated using X-ray diffraction and X-ray reflectivity method. Systematic thickness and substrate dependence studies with different growth and post-deposition annealing conditions have been carried out. We show that a sharp Bi2Se3/Co interface is possible, but annealing may lead to significant interdiffusion. Shadow mask techniques were incorporated to define micron-sized TMR devices. Detailed transport and magnetotransport and current-voltage characteristics will be discussed.