Eur. Phys. J. B 21, 67-73 (2001)
https://doi.org/10.1007/s100510170214

Magneto-optical Faraday and Kerr effect of orthoferrite thin films at high temperatures

¹ Laboratoire de Magnétisme et d'Optique, Université de Versailles - CNRS, bâtiment Fermat, 45 avenue des États-Unis, 78035 Versailles Cedex, France
² Institute of Physics, Charles University, Ke Karlov 5, 121 16 Prague 2, Czech Republic
³ Departamento de Física, Faculdade de Ciências, Universidade do Porto, Rua Campo Alegre 687, 4169 007 Porto, Portugal
⁴ Département de Physique, Université de Versailles, 45 avenue des États-Unis, 78035 Versailles Cedex, France

Corresponding author: ^a keller@physique.uvsq.fr

Received: 28 July 2000
Published online: 15 May 2001

Abstract

Orthoferrites present, as bulk materials, reorientation transitions of their magnetic moment alignment at temperatures depending on the rare-earth (RE) ion. In particular, orthoferrites (REFeO₃) with RE = Sm, Dy, present this transition at K and 36 K, respectively. The spectra of the complex Kerr and Faraday angle have been measured on orthoferrite thin films (RE = Sm, Dy, Y), which were prepared by pulsed laser deposition on amorphous quartz substrates. The obtained spectra exhibit contributions of both surfaces and interfaces. Propagation effects of the polarized light in the magneto-optical medium which is interpreted in terms of a simplified theoretical formalism, is also observed. For selected photon energies, temperature dependent Faraday rotation measurements, , on orthoferrite thin films (RE = Sm, Dy, Y) have been performed. A quite different thermal variation compared to the bulk magnetization has been observed. Curie temperatures are found to be close to the bulk values or slightly larger by 10 K to 20 K as in the case of DyFeO₃ and YFeO₃. For RE = Sm and Dy, increases with increasing temperature contrary to the saturation magnetization, passes through a maximum at about 460 K and vanishes with a T_C of K, 695 K for RE = Sm and Dy respectively.