Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1802010 | Journal of Magnetism and Magnetic Materials | 2009 | 6 Pages |
Abstract
New photo-magnetic effects with an indefinitely long-time memory are found at room temperature in the epitaxial Mg0.75Mn0.21Co0.04Fe2O4 ferrite film. Illumination of the ferrimagnetic material with low-intensity (0.4Â WÂ cmâ2) circularly polarized light with or without a static magnetic field in the Faraday effect geometry results in a number of nonlinear effects in both space and time. In a uniform crystal with cubic symmetry, the long-lived photo-induced magnetization (PIM) with a unidirectional anisotropy appears along the direction of the incoming light. The effects depend on a combination of magnetic field H and the helicity of circularly polarized light Ï. Two combinations H+,Ï+ and Hâ,Ïâ lead to a photo-induced unidirectional anisotropy with a shift of the hysteresis loop along an applied field and a change in loop parameters. The loop contracts by a factor of two, the shift of the mid-point Hsh increases by factor of five surpassing the coercivity Hc, the coercivity Hc1 and remanence Mr1 (for decreasing applied field) reverse the sign, increasing by 9Â Oe and reducing by a factor of 4.5, respectively. The effects cannot be erased by a conventional demagnetization (using an AC current that is reduced to zero amplitude), but can be removed using an illumination with two other combinations (H+,Ïâ and Hâ,Ï+) as well as by heating at temperatures higher than the Curie temperature. This long-lived room-temperature memory effect may arise from the formation of complex photo-induced defects including photo-induced magnetic polarons. The possible mechanisms responsible for the appearance of a room-temperature photo-induced unidirectional anisotropy with a long-lived memory are discussed. These new photo-magnetic effects may find an application in magneto-optical memory devices.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Condensed Matter Physics
Authors
E.Z. Katsnelson, M.M. Chervinsky,