The dependence of magnetization on the magnetic field (up to 50000 Oe) was studied using a SQUID magnetometer S700 (Cryogenic, UK) at temperatures of 4.2 and 290 K. In addition, the temperature dependence of the magnetization was measured in two regimes. In zero-field-cooled (ZFC) measurements, the samples were cooled from room temperature to 2 K in zero field. Then, when the temperature reached 2 K, a magnetic field of 1000 or 10000 Oe was applied and the magnetization was measured when heated to 150 or 300 K. For field-cooled (FC) measurements, samples were cooled from room temperature to 2 K in a preset magnetic field, and then data were collected while heating in a manner similar to ZFC.