Giant Bulk Photovoltaic Effect under Linearly Polarized X-Ray Synchrotron Radiation

The angular dependencies of the linear bulk photovoltaic effect (BPE) under linearly polarized x-ray synchrotron radiation in LiNb${\mathrm{O}}_3$: Fe, ${\mathrm{La}}_3$ ${\mathrm{Ga}}_5$Si${\mathrm{O}}_{14}$: Pr, and Si${\mathrm{O}}_2$ have been revealed. This is the first observation of the tensorial properties of BPE under polarized x rays, which reveals giant values of the components of the photovoltaic tensor $G_{\mathrm{ijk}}$. The values of $G_{\mathrm{ijk}}$ at 850 eV are 3-6 orders of magnitude higher than the corresponding values for the optical region. The present results may also explain the origin of x-ray photorefractive effect previously observed in LiNb${\mathrm{O}}_3$: Fe.