Magnetorefractive and Kerr effects in the [La0.67Ca0.33MnO3/La0.67Sr0.33MnO3]n superlattices

• Giant magnetorefractive effect in manganite superlattices was studied in the infrared.
• Increase in magnetotransmission of superlattices relative to a single layered film was detected.
• Influence of intermixing effects at interfaces and deviations of composition of layers was studied.
• Resonance-like bands in magnetoreflection spectra of the superlattices are observed.

It is demonstrated that in the [La0.67Ca0.33MnO3(d = 9 nm)/La0.67Sr0.33MnO3(9 nm)]3 and [La0.67Ca0.33MnO3(9 nm)/SrTiO3(2 nm)/La0.67Sr0.33MnO3(9 nm)]3 superlattices with the interlayer barriers of nonmagnetic dielectric SrTiO3, the magneto-optical Kerr and magnetorefraction (magnetoreflection and magnetotransmission of unpolarized light) effects have large values close to those for the heterostructures of the same composition. The defects and strain in the layers and at interfaces of superlattices result in appearance of additional band in the Kerr effect spectrum, temperature hysteresis, and abnormal temperature dependence of the Kerr effect. It is shown, that the resonant-like contribution to the magnetoreflection spectra of superlattices is due to the shift of the minima in reflection coefficient near the phonon bands by magnetic field. The increase in magnetotransmission of superlattices relative to a single layered film is due to multiple transmission of light through the layers of superlattices. The intermixing effects at interfaces and deviations of composition of layers from stoichiometry both influence the values of magnetorefraction effect in superlattices and the shapes of their temperature dependences.