The initial magnetic susceptibilities of Gd3Fe5O12 and Tb3Fe5O12 in the compensation point region

Abstract The initial magnetic susceptibilities of polycrystalline GdIG and TbIG have been measured by Gouy's method around their compensation points (288 K for GdIG; 248 K for TbIG). The temperature dependences of the susceptibilities are characterized by small jump and inflection at T comp. ± (10−12) K. A peak of d.c. susceptibility at 5 K above T comp. appears only in first run (cooling to low temperatures in the absence of external field and then measuring during the heating of the sample). The two parts of the complex susceptibility are determined for TbIG (single and polycrystals) and for polycrystalline GdIG, and are found close to zero in the T comp. vicinity. The peak of d.c. susceptibility and zero values of χ′ near T comp. are attributed to the domain structure changes.