Tb-CONTAINING RARE EARTH-ALUMINUM GARNET CERAMIC, AND METHOD FOR MANUFACTURING SAME

[Problem] To provide a Tb-containing rare earth-aluminum garnet ceramic which : has a Verdet constant of substantially the same level as that of a TGG single crystal used in an isolator; has an insertion loss and extinction ratio equal to or greater than those of a TGG single crystal; generates less heat when a high-power laser is applied thereto; and is less likely to cause a thermal lens effect or thermal birefringence. [Solution] The present invention relates to : a Tb-containing rare earth-aluminum garnet ceramic characterized by containing a garnet polycrystal represented by the compositional formula (TbxRe1-x)3(AlySc1-y)5O12 (therein, Re represents at least one among Y and Lu, x=1.0-0.5, and y=1.0-0.6), and containing Si and at least one of Ca and Mg; a method for producing the same; and an isolator device using the ceramic.