Fabrication and thickness-dependent magnetic studies of tunable multiferroic heterostructures (CFO/LSMO/LAO)

This study investigates the structural and magnetic properties of LaAlO₃(LAO)/La_0.7Sr_0.3MnO₃ (LSMO)/CoFe₂O₄(CFO) heterostructures grown by pulsed laser deposition. X-ray diffraction analysis illustrates the crystalline oxide growth and the rocking curve measurement along the (200)-peak of LSMO show a small FWHM (0.37°), which indicates an excellent out-of-plane orientation of the film. Transmission electron and scanning electron energy-dispersive X-ray spectroscopy confirms the homogeneous distribution of structural and elemental composition of the heterostructure. From the static magnetic measurements in the LSMO films at room temperature, we report the presence of a ferromagnetic hysteresis loop with a coercive field of 327 Oe. In addition, we have examined the effect of CFO layer thickness on the ferromagnetism of LSMO and obtained improved magnetic properties with a maximum coercive field of 792 Oe in CFO/LSMO heterostructure for an optimum CFO thickness of ~ 40 nm. From the dynamic magnetic measurements using ferromagnetic resonance spectroscopy, we have obtained a low Gilbert damping parameter of ~ 0.037 for the LSMO/LAO structure due to spin–orbit coupling. Besides, the small gyromagnetic ratio (0.002 GHz/Oe) of the same film is quite promising to design spin valve and magnetic tunneling-based devices.