| abstract |
(1) or a complex oxide represented by the following formula (1) and having a Berde constant at a wavelength of 1064 nm of not less than 0.14 min / (Oe 占) m) Optical material which is suitable for constituting a magneto-optical device such as an optical isolator which does not absorb fiber laser light having a wavelength of 0.9 to 1.1 탆 and does not generate a thermal lens and whose Verde constant is larger than that of a TGG crystal do. Tb 2 R 2 O 7 (1) Wherein R is at least one element selected from the group consisting of silicon, germanium, titanium, tantalum, tin, hafnium and zirconium (except for silicon, germanium and tantalum, |