Optically induced variation of magnetic and photoelectric properties of ferrites

The laser irradiation of ferrites in a dc magnetic field at room temperature leads to a significant change of their residual magnetization and photovoltaic response, both in magnitude and the symmetry with respect to a magnetic field. The photovoltage also acquires a nonlinear field dependence. The variation in the properties is retained by the samples for a long time. This lifetime strongly depends on the wavelength of the laser light. Photoinduced effects are connected with photomagnetization (PM) which arises during irradiation. The PM was directly measured with a magnetometer on single crystal Mn1−xZnxFe2O4 ferrites (bulk) with x=0.09 (1) and 0.56 (2) as well as on MeFe2O4 ferrite films with Me=Mn (3), Ni (4), and Co (5). The effect might be useful for optical recording.