BI-SUBSTITUTED RARE EARTH IRON GARNET SINGLE CRYSTAL, METHOD FOR PRODUCING SAME, AND OPTICAL DEVICE

摘要

[Problem] To provide a garnet single crystal which is obtained using a platinum crucible, does not contain lead, is free from quality deterioration and has good mass productivity, while having an IL of 0.10 dB or less. [Solution] A Bi-substituted rare earth iron garnet single crystal, which has a composition represented by R_3-xBi_xFe_5-wA_wO₁₂ (wherein R represents one or more rare earth elements that are selected from the group consisting of Tb, Y, Eu, Gd, Ho, Yb, Lu, Nd, Tm, La, Sm, Dy, Er, Ce and Pr and inevitably include Tb; A represents one or more elements that are selected from the group consisting of Ga, Al, In, Sc, Co, Ni, Cr, V, Ti, Si, Ge, Mg, Zn, Nb, Ta, Sn, Zr, Hf, Pt, Rh, Te, Os, Ce and Lu; x satisfies 0.7 x ≤ 1.5; and w satisfies 0 w ≤ 1.5), and which contains Pt but does not contain Pb. The Bi-substituted rare earth iron garnet single crystal additionally contains Mn or at least one group 2 element. When Mn or at least one group 2 element is represented by M, the concentration (at ppm) of M in the Bi-substituted rare earth iron garnet single crystal is represented by [M], the Pt concentration (at ppm) is represented by [Pt], and the relational expression ∆ between [M] and [Pt] is expressed as ∆ = [M] - (α × [Pt]), the coefficient α is set at a value within the numerical range of 0.91 ± 0.05 and ∆ is set at a value within the range from -7.23 at ppm to 1.64 at ppm (inclusive).