Structural Phase Transition and Tunable Exchange Bias Effect in La1·5Sr0·5CoMnO6 Nanoparticles with Particle Size

The effect of particle size on the crystal structure and magnetic behaviors of the double perovskite oxide La1.5Sr0.5CoMnO6 was systematically investigated. As the particle size increases from 45 nm to 308 nm, the crystal structure undergoes a gradual transformation from a cubic phase with the Pm-3m space group to the rhombohedral phase (R-3c). The magnetic data reveals that the Griffiths phase (GP) can be induced and enhanced by an increase in particle size. Importantly, the modulation of the conventional and spontaneous exchange bias (EB) of the system was effectively achieved by crystal growth, i.e., a monotonically increased EB field with an increase of particle size. This phenomenon can be attributed to the enhancement in the antiferromagnetic (AFM) interfacial anisotropy based on the Meiklejohn-Bean model. Our results provide evidence that crystal growth plays a crucial role in modulating the EB effect in double perovskite.