Structural and magnetic studies of Y3Fe5−5xMo5xO12

• M(H,T) data indicate the long range ferrimagnetic ordering in Mo doped YIG (MYIG).
• Cubic anisotropy constant decreases with temperature.
• Magnetic moment per Fe atom in the unit cell initially increases with Mo doping.
• Rietveld analysis indicate initial occupancy of Mo ions at Fe octahedral sites.
• Raman shift of T2g vibrational mode in MYIG indicates preferential substitution.

We report the role of molybdenum (Mo) doping in ferrimagnetism of yttrium iron garnet Y3Fe5O12 (YIG). X-ray diffraction studies in conjunction with Rietveld refinement indicate that the Y3Fe5−5xMo5xO12 (MYIG) crystallizes in the crystal symmetry of inverse cubic spinel phase. Temperature and field dependent magnetization M(H,T) data designate the long range ferromagnetic ordering in MYIG. The calculated cubic anisotropy constant K1(T) and saturation magnetization Ms(T) by the ‘law of approach’ indicate that these parameters decrease with increasing temperature. The magnitude of Ms(T) is dependent on Mo-concentration and the Ms–T functional relationship obeys the Bloch׳s spin wave theory. Initially magnetic moment per Fe atom in the unit cell increases with Mo doping and henceforth it decreases slowly with further Mo doping. XRD and Raman spectroscopic molecular vibrational studies were employed to explain the variation of magnetic moment per Fe atom in MYIG. The occupancy parameter and magnetic moment calculated by Rietveld analysis reveal that Mo ions occupy the Fe position at the octahedral site with low doping and this site occupancy decreases with increase in Mo doping.