Microscopic origin of optical absorption for Bi-YIG magneto-optic thin film

摘要

The density of states and orbital energies of (Y$+3$PLU$/Fe$+3$PLU$/$-6$/O$+2$MIN$/$-8$/)$+5$PLU$/ cluster of YIG and (Bi$+3$PLU$/Fe$+3$/$-6$/O$+2$MIN$/$-8$/)$+5$PLU$/ cluster of Bi-YIG are calculated by using DV-X$alpha method. The wavefunctions of some orbits of clusters are given. From total density of state and wavefunctions, it is found that the spin-orbit interaction is increased by the formation of molecular orbit between 3d orbital in Fe$+3$PLU$/ and 6p orbital in Bi$+3$PLU$/ having a large spin-orbit interaction coefficient and the oscillator strengths of transitions are increased because of bismuth substitution. There are two types of charge transfer transition between $MIN@3.2 approximately 3.2 eV on the basis of the total density of energy states of YIG and Bi-YIG films. The optical absorption spectra of Bi-YIG are calculated while x $EQ 0, 0.4, 1.0 in the wavelength from 0.5 $mu@m to 0.9 $mu@m. The dependence of absorption coefficient $alpha on transition linewidths $Gamma@, and spin-orbit splitting energies $Delta$-i$/ of coupling orbits are investigated respectively. The influence of Bi$+3$PLU$/ ion on optical absorption is obtained.