Interplay of Hanle effect and superparamagnetism in Pt/hexagonal lutetium ferrite bilayers*

Hanle magnetoresistance (MR), which is caused by dephasing of spin accumulation at boundaries due to spin precession and diffusion in a magnetic field, has been observed in heavy metal thin films with strong spin-orbit coupling, and provides a simple way to derive spin transport properties. By forming an interface between platinum (Pt) and hexagonal lutetium ferrite and measuring field-dependent and angle-dependent MR in Pt, we have observed pronounced longitudinal Hanle MR and corresponding transverse Hall effect at room temperature. Negative MR and anomalous Hall effect emerge and dominate at lower temperatures, which is reminiscent of the giant MR in granular magnetic solids. The results indicate that superparamagnetic clusters have formed at the interface and modified the spin transport properties of the Pt layer.