Anomalous photovoltaic effect in ferroelectrics

The recently discovered anomalous photovoltaic effect in ferroelectrics is attracting considerable attention of specialists in ferroelectricity and solid-state physics. The anomalous nature of the effect is manifested by the fact that the photo-emf developed in ferroelectrics and pyroelectrics is many orders of magnitude greater than the band gap and can reach 10$^3$–10$^5$V. The anomalous photovoltaic effect in ferroelectrics has found extensive applications in volume phase holography. A review is given of the experimental investigations of the anomalous photovoltaic effect in ferroelectrics and also of the models proposed to explain this effect.