Magneto-optical Kerr spectroscopy of platinum

Abstract

Magneto-optical (MO) response of paramagnetic Pt is reported. The magneto-optical polar Kerr effect spectra of the paramagnetic fcc Pt metal film were measured with high sensitivity in an applied magnetic field of 1.5 T over the photon energy range 0.74--5.6 eV. It is shown that the ab initio linear muffin-tin orbital (LMTO) calculations reproduce the experimental spectra well and allow us to explain the microscopic origin of the Pt magneto-optical response in terms of interband transitions. The importance of the off-diagonal intraband Drude-like transitions is demonstrated explicitly and found to be the predominant contribution to the observed spectra in the ir range. The band-by-band decomposition of the fcc Pt MO spectra is presented and the interband transitions responsible for the prominent structures in the spectra are identified. The contributions coming from the vicinity of high-symmetry points of the Brillouin zone are quantitatively determined. A comparative study of the relation between the main spectral features in the Pt and Pd metals and the peculiarities of their band structures is performed. It is shown that the individual interband transitions arising from the same points of k space characterize essentially similar spectral shapes in both metals, but due to different energy locations they result in different optical and MO spectra. The influence of the magnetic field and spin-orbit coupling on the MO interband transitions in Pt is discussed. The crucial role of the transitions involving the states near the Fermi level is elucidated.