Ferromagnetic–Antiferromagnetic Coupling by Distortion of Fe/Mn Oxygen Octahedrons in (BiFeO₃)_m(La_0.7Sr_0.3MnO₃)_n Superlattices

Interface enhanced magnetism attracts much attention due to its potential use in exploring novel structure devices. Nevertheless, the magnetic behavior at interfaces has not been quantitatively determined. In this study, abnormal magnetic moment reduction is observed in La_0.7Sr_0.3MnO₃ (LSMO)/BiFeO₃ (BFO) superlattices, which is induced by ferromagnetic (FM)/antiferromagnetic (AFM) coupling in the interface. With reduced repetition of the superlattice's unit cell [(LSMO)_n/(BFO)_n]_{60/ n} (n = 1, 2, 5, 10) on a SrTiO₃ substrate, magnetic moment reduction from 25.5 emu cc⁻¹ ([(LSMO)₁₀/(BFO)₁₀]₆) to 1.5 emu cc⁻¹ ([(LSMO)₁/(BFO)₁]₆₀) is obtained. Ab initio simulations show that due to the different magnetic domain formation energies, the magnetic moment orientation tends to be paramagnetic in the FM/AFM interface. The work focuses on the magnetic domain formation energy and provides a pathway to construct artificial heterostructures that can be an effective way to tune the magnetic moment orientation and control the magnetization of ultrathin films.