Magnetic properties of nanocrystalline Ni0.7Mn0.3Gd0.1Fe1.9O4 ferrite at low temperatures

Mössbauer spectra and magnetic measurement of Ni0.7Mn0.3Gd0.1Fe1.9O4 ferrite were investigated by Oxford MS-500 Mössbauer spectrometer and superconducting quantum interference device (SQUID) magnetometer with a field 5 T. Ni0.7Mn0.3Gd0.1Fe1.9O4 nanoparticles have a considerable coercivity of 1040 Oe when the test temperature is reduced to 2 K. Mössbauer spectra show that Ni0.7Mn0.3Gd0.1Fe1.9O4 nanoparticles exhibit superparamagnetism at room temperature and ferrimagnetism at 77 K.