We have observed photocarrier transport behaviors in ${\mathrm{BiFeO}}_3/{\mathrm{La}}_{1-x}{\mathrm{Sr}}_x{\mathrm{MnO}}_3$ (BFO/LSMO) heterostructures by using time-resolved synchrotron x-ray magnetic circular dichroism in reflectivity. The magnetization of LSMO layers was used as a probe of photo-induced carrier dynamics in the photovoltaic BFO layers. During the photo-induced demagnetization process, the decay time of LSMO ($x$=0.2) magnetization strongly depends on the ferroelectric polarization direction of the BFO layer. The variation of decay time should be attributed to the different sign of accumulated photocarriers at the BFO/LSMO interface induced by the photovoltaic effect of the BFO layer. The photocarriers can reach the BFO/LSMO interface and influence the magnetization distribution in the LSMO layers within the timescale of $\sim 100$ ps. Our results provide a novel strategy to investigate carrier dynamics and mechanisms of optical control of magnetization in thin film heterostructures.

Close

PrevNext

View figure in article

• Photovoltaic effect
• Spin dynamics
• Multiferroics
• Pump-probe spectroscopy
• Resonant elastic x-ray scattering