First-principles study of photogalvanic effects in magnetic ferroelectrics

Photogalvanic (Bulk photovoltaic) effects have been extensively studied in ferroelectric materials having broken inversion symmetry in past years. However, the study of magnetism-induced photogalvanic currents is still missing in magnetic ferroelectrics BiFeO₃ and PbNiO₃ which possess large electric polarization of 90 μC/cm² and 100 μC/cm² respectively. In this work, we systematically study the linear and circular photogalvanic effects, namely, linear and circular shift and injection currents. Our preliminary calculations have shown that the linear shift current conductivity can go up to 72 μA V^-2 & -34 μA V^-2 whereas it goes as high as -8 μA V^-2 & -2 μA V^-2 for circular shift current conductivity within the energy range of 0 - 6 eV for multiferroic (magnetic ferroelectrics) BiFeO₃ and PbNiO₃ respectively. Linear injection current susceptibility is 43 × 10⁸ A V^-2 s^‑1 and 6 × 10⁸ A V^-2 s^‑1 for BiFeO₃ & PbNiO₃ respectively in the 0 – 6 eV energy range. Circular injection current susceptibility has a large value of about 21×10⁸ A V^-2 s^‑1 and -66 × 10⁸ A V^-2 s^‑1 for BiFeO₃ and PbNiO₃ respectively within 0 - 4 eV energy range. Thus, we believe that magnetic ferroelectrics BiFeO₃ and PbNiO₃ will have promising applications in ferroelectric-based photovoltaic devices.