Manipulation of spin and the effective spin-orbit coupling in complex oxides*

Electric field manipulation of spins and control of spin-orbital coupling have stimulated an intense interest due to their promise for new functionalities and power efficient device concepts. We are particularly interested in the manipulation of spin state (high spin to low spin) as well as their directionality, for example in a d⁵ state Fe³⁺ ion. Using Fe-doped PbTiO₃ (Fe-PTO) as a model system, we present a systematic study of the thickness, temperature and electric field-dependent spin manipulations and spin-orbit coupling (SOC) effect in dilute magnetic ferroelectrics. Using laser MBE, we synthesized a series of Fe-PTO thin films with thickness range from 15 nm to 200 nm on various substrates in order to access systematically strained states in the Fe-PTO layer. Electron spin resonance from the Fe-site demonstrates a strong g-factor anisotropy from the normal to in-plane direction of the films. Moreover, we observed that the g-factor anisotropy systematically changes under tensile strain. These results demonstrate the manipulation of spins as well as effective SOC by subtle aspects of lattice strain/electric field.