Optical and magneto-optical properties of Nd_(0.5)Gd_(0.5)Fe_3(BO_3)_4 single crystal in the near IR spectral region

摘要

Polarized optical absorption and magnetic circular dichroism (MCD) spectra of the trigonal multiferroic Nd_(0.5)Gd_(0.5)Fe_3(BO_3)_4 were studied in the region of transitions ~4I_(9/2) - > ~4F_(3/2) and ~4I_(9/2) - > (~4F_(5/2) + ~2H_(9/2)) in Nd~(3+) ion. Components of the crystal field splitting of the states were identified with the help of MCD and polarized absorption spectra. Splitting of the Nd~(3+) absorption lines caused by the magnetic ordering were observed. Splitting of Nd~(3+) ground state in Fe-sublattice exchange field was found to be ~9 cm~(-1) at 5.7 K. The Zeeman splitting of some absorption lines in the external magnetic field and changes of the effective Lande factors in the C_3-direction as a result of the corresponding optical transitions were found. Peculiarities in the temperature behavior of the absorption lines connected both with the ground and excited states were revealed. Peculiarities connected with the excited states testify to the local crystal distortions in the excited states.