Asymmetric Magnetoresistance in a 3 d -5 d -Based La0.67Ca0.33MnO3/SrIrO3 Bilayer: The Role of Unidirectional Anisotropy

The complex interplay between spin–orbit coupling, magnetism, and magnetic field at the interface of a heterostructure, consisting of ferromagnet (FM) and heavy metal (HM), often exhibits extraordinary magnetic and electric phenomena, where an in-plane Dzyaloshinskii–Moriya (DM) interaction plays a crucial role in stabilizing local spin texture in the FM layer. Here, we report detailed magnetic and magneto-transport behavior on an epitaxially grown thin heterostructure with 3d FM La0.67Ca0.33MnO3 (LCMO) and 5d HM SrIrO3 (SIO). Magnetic measurements show an unusual development of magnetic ordering in SrIrO3 around 42 K, which further leads to a Mn/Ir magnetic coupling at the interface. The magnetoresistance (MR) measurements show an evolution of its value and shape with the magnetic state of this bilayer. While MR is negative at high temperatures, it shows a positive-to-negative crossover with stable magnetic ordering of LCMO, and finally, the positive MR exhibits an asymmetry at low temperatures with the ordering of SIO. While we ascribe this unusual MR behavior to interface-driven varying spin scattering between itinerant and localized electrons, our results shed light on comprehending the complex but tunable interface behavior on charge transport in a particularly designed heterostructure, offering valuable insights for future functional material engineering.