The origin of the 90 degree magneto-optical Kerr rotation in CeSb

TL;DR

This paper explains the origin of the 90-degree magneto-optical Kerr rotation in CeSb by calculating its spectral response, revealing that nonmagnetic optical properties primarily cause large polarization rotations.

Contribution

The study provides an exact calculation of Kerr rotation in CeSb, linking large polarization rotations to nonmagnetic optical properties and identifying conditions for 180-degree rotations.

Findings

Kerr rotation reaches 90 degrees at 0.46 eV in CeSb.

Kerr rotation can jump to -90 degrees at lower energies.

Nonmagnetic properties mainly cause large polarization rotations.

Abstract

We calculate the linear magneto-optical Kerr rotation for CeSb in the near-infrared spectral range. Using an exact formula for large Kerr rotation angles and a simplified electronic structure of CeSb we find at \hbar \omega = 0.46 eV a Kerr rotation of 90 degree which then for decreasing \omega jumps to -90 degree as recently observed. We identify the general origin of possible 180 degree polarization rotations as resulting from mainly nonmagnetic optical properties, in particular from the ratio of the dominant interband resonance frequency to the plasma frequency. The dependence of the Kerr rotation on moments and magnetization is discussed.