Observation of Giant Effective Orbital Hall Angle in Ti/Pt Metallic Heterostructure

Orbitronics is an emerging field in which orbital currents are used to develop high-efficiency electronic information devices. Orbital currents have a wider material range and longer transmission distance than spin currents. However, the efficient utilization of orbital currents remains challenging. In this paper, the study reports a giant effective orbital Hall angle in a Ti/Pt metallic heterostructure for efficient magnetization switching. The effective orbital Hall angle of Ti/Pt/Permalloy (Ni₈₁Fe₁₉) reaches 2.4 ± 0.5, a 14-fold increase relative to that of Ti/Ni. By constructing an interface orbital current transmission model, the study found that the effective orbital Hall angle is closely related to the interface spin-orbit coupling. In addition, research obtained a critical magnetization switching current density of Ti/Pt as low as 5.7 × 10⁵ A/cm², which is comparable to that of topological insulators. Based on this metallic heterostructure, the study demonstrates high-efficiency and low-dissipation Boolean logic operation. These metallic heterostructures, which combine a large effective orbital Hall angle and ease of integration with semiconductors, have significant implications for large-scale orbitronic device applications.