Antiferromagnetic superexchange interaction between Fe3+ ions in Fe3+ doped wide-gap oxide of β-Ga2−Fe O3 (x=0.1, 0.2, 0.3, 0.4)

Abstract

In the Fe 3+ doped wide-gap oxide of β-Ga 2− x Fe x O 3 ( x =0.1, 0.2, 0.3, 0.4), Rietveld refinements of the X-ray diffraction data show that the Fe 3+ ions are preferentially occupied on the octahedral sites. From the measurements of magnetization as a function of magnetic field and inverse molar susceptibility as a function of temperature, it is found that the superexchange interaction between Fe 3+ ions via an intermediate oxygen ion is antiferromagnetic. The optical bandgap ( E g ) is found to decrease monotonically in energy upon increasing the Fe 3+ concentration. Below the E g edge, optical absorption subspectra are observed to occur at ~1.8 and ~2.7 eV, which are attributed to the d – d transitions of the crystal-field splitting of 3 d 5 multiplets of the octahedral Fe 3+ ion. • Preferential replacement of Ga 3+ by Fe 3+ ions occurs on the octahedral sites of β-Ga 2 O 3 . • The superexchange interaction between Fe 3+ ions in β-Ga 2 O 3 is antiferromagnetic. • The optical bandgap decreases monotonically upon increasing Fe 3+ content.