Temperature dependent Mueller matrix of magnetized Ni near the Curie temperature

Optical properties of magnetized Ni are studied in polar configuration. The temperature dependence of the optical constants of magnetized Ni 1000 Å demonstrates an anomaly near the Curie temperature T_c.

Assuming that magnetized Ni is not depolarizing, the MM is derived up to the first order of Voigt parameter from the Jones matrix. Using spectroscopic ellipsometry at an incident angle of 70° and a UHV cryostat we took three dynamic measurements in a temperature range between 400 and 770 K. The experimental MM describes significant changes in the on-diagonal and negligible ones in off-diagonal blocks about T_c. The authors believe that the changes in off-diagonal elements are due to the magneto-optical Kerr effect.

However, the considerable changes of the on-diagonal blocks of the MM indicate that the variations in optical constants about T_c come from the diagonal elements of the dielectric tensor, which is described by Drude response. This means that either the scattering rate or the carrier density changes under magnetization. Furthermore, inverting the direction of the magnetization shows that all elements of the MM depend only on the magnitude of the magnetization, not the direction. This is in contrast to the theoretical MM.