Absortion and magnetic circulation dichroism of a 6A1 4E transition for Fe(III) in Y3Al5O12 : Evidence for a single-ion mechanism and two tetrahedal sites

摘要: Abstract The absorption and magnetic circular dichroism spectra of Y 3 Al 5-x Fe x O 12 (x ≤ 0.017) crystals have been measured over a wide range temperatures. In contrast with the situation encountered for yttrium iron garnet, electronic transitions our dilute materials are shown to be allowed by usual single ion (and not exchange induced) electric dipole mechanism. temperature dependence proves that main bands correspond at tetrahedral sites. Furthermore, two states assigned as 4 E (24 120 cm −1 ) T 1 (around 24 500 on basis sign magnitude corresponding dichroism. Finally, measurements sharpest lines in provide spectroscopic evidence types tetragonally distorted