Giant magnetorefractive effect in La 0.7 Ca 0.3 MnO 3 films
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Giant Magnetorefractive Effect in La0.7Ca0.3MnO3 Films A. B. Granovskiia, Yu. P. Sukhorukovb, A. V. Teleginb, V. D. Bessonovb, E. A. Gan’shinaa, A. R. Kaul’a, I. E. Korsakova, O. Yu. Gorbenkoa, and J. Gonzalezc a
Moscow State University, Moscow, 119991 Russia email: [email protected] b Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620990 Russia email: [email protected] c Departamento Fisica de Materiales, Facultad de Quimica, Universidad del Pais Vasco 20009, San Sebastian, Spain Received June 1, 2010
Abstract—Complex experimental investigations of the structural, optical, and magnetooptical properties (magnetotransmission, magnetoreflection, and transversal Kerr effect, as well as the magnetoresistance, of La0.7Ca0.3MnO3 epitaxial films indicate that magnetoreflection and magnetotransmission in manganite films can reach giant values and depend strongly on the magnetic and charge homogeneity of the films, their thick ness, and spectral range under investigation. It has been shown that the optical enhancement of the magne torefractive effect occurs in thin films as compared to manganite crystals. In the region of the minimum of the reflectance near the first phonon band, the resonancelike magnetorefractive effect has been observed, which is accompanied by change of the sign of the magnetoreflection. A model based on the theory of the magnetorefractive effect has been proposed to qualitatively explain this behavior. DOI: 10.1134/S106377611005105X
1. INTRODUCTION The possibility of the highspeed control of the propagation and polarization of light is actively investi gated in view of the development of the optical methods of the transmission and processing of information, holography, optical computers, contactless sensors, etc. The highest performance speed is inherent in magnetic materials in which the reorientation of the magnetic moment or magnetization can occur in times certainly shorter than nanoseconds. The efficiency of the high speed control of the propagation direction and modula tion of light by means of a magnetic field and magneto optical effects, in particular, using magnetophotonic crystals was confirmed experimentally [1]. However, traditional Faraday and Kerr magneto optical effects are small because of their relativistic origin [2]. For this reason, it is necessary to seek new magnetooptical effects and corresponding functional materials for solving this problem. One of such prom ising effects is the magnetorefractive effect, which is a magnetic fieldinduced change in the reflection and transmission (absorption) of natural light in magnetic materials having large magnetoresistance [1, 3, 4]. In contrast to traditional magnetooptical phenomena, the magnetorefractive effect is not attributed to the spin–orbit interaction; hence, the magnetoreflection and magnetotransmission of light due to the magne torefractive effect can reach giant for magnetooptics values of 10–20% [3, 4]. The magnetorefractive effect is most pronounced in manganit
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