Interfacial Magnetic Features of La₂CoMnO₆/Pt Bilayers Studied by Using Spin Hall Magnetoresistance

Abstract Spin Hall magnetoresistance (SMR) is used to study interfacial magnetic features in La₂CoMnO₆ (LCMO)/Pt bilayers. LCMO is a ferromagnetic insulator with a Curie temperature T_c = 250 K and a strong magnetic anisotropy that can be tuned by microstructural strain. However, SMR measurements do not show any dependence on the strained state of the LCMO films. In addition, contrary to what may be expected, SMR signal persists above T_C exhibiting a strong magnetic field dependence well above the saturation of the magnetization while the typical hysteresis on crossing H = 0 is absent. All these results suggest that the uppermost LCMO interfacial layers are magnetically uncoupled from the rest of the LCMO film and they do not show long range magnetic ordering. This fact is confirmed by a complete scanning transmission electron microscopy study of the interface that makes evident that the last atomic layers of the LCMO film do not contain Co and have a LaMnO_3+δ simple perovskite‐like structure with the last atomic layer being lanthanum oxide. The analysis of the experimental results according to recent SMR theories indicates, in fact, that the LCMO interfacial layer behaves as a 2D Heisenberg ferromagnet.