Polycrystalline and nanocrystalline samples of the CuCr2Se 4 ferromagnetic spinel are synthesized. The mean size of nanocrystals is 50 nm. The Curie temperature of spinel nanocrystals (465 K) is higher than that of spinel polycrystals (435 K). Laser irradiation at a wavelength of 1.5 μm (in an external magnetic field) increases the magnetization of the noncrystalline powder. Most likely, this can be explained by the change in the orientation of magnetic moments of single-domain nanoparticles. The observed effect reaches a maximum in magnetic fields with a strength lower than that of the saturation field.
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ACKNOWLEDGMENTS This work was supported by the Russian Foundation for Basic Research, project no. 04-03-33049.