sputtered thin films

Topological Insulators (TI) are a recent category of materials. 3D TIs host a protected metallic state on their surface while having an insulating bulk. The state appears in the form of a spin-textured Dirac cone. Due to these properties, several applications are foreseen. However, a better fundamental understanding of the relationship between the TI surface and bulk states is required.

In this paper, the structural and electrical properties of a uniform nanocrystalline Sb₂Te₃ thin film fabricated by ion beam sputtering will be reported. We show that the thin film bulk conduction is dominated by Variable Range Hopping. However, the presence of the weak antilocalization cusps on the magnetoresistance at low temperatures and low magnetic fields is also analyzed and found to be consistent with the existence of a TI surface state, having a phase coherence length of ~60 nm and a single 2D channel open at 2 K. Following these properties, the preliminary results of ferromagnetic resonance spin current generation and magnetization control of Sb₂Te₃ - Py thin films bilayers will be discussed, including our estimate of the spin Hall angle. As these bilayers were made using a scalable inexpensive method, the results offer promising opportunities for future applications in spintronics.