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The magnetic properties of Ni 1.5 Fe 1.5 O 4 ferrite have been investigated using the techniques of dc magnetometry and Mӧssbauer spectroscopy. The material has been prepared by chemical reaction of metal nitrates at different pH values and subsequently, annealed at different temperatures to improve the microstructure. The samples with single-phased cubic spinel structure have been used for magnetic study. The material showed a variety of magnetic features, including superparamagnetic and soft ferromagnetic properties. At room temperature, changes of the ferromagnetic parameters of the material have been found in the range 0–47 emu/g for spontaneous magnetization, 0–0.37 for squareness, and 0–195 Oe for coercivity. Variation of the pH value during chemical reaction and changes of the grain size by thermal treatment played an important role in tuning the coexisting superparamagnetic and ferromagnetic components in the material. Samples prepared at high pH value showed small grain size and superparamagnetic features, whereas the samples prepared at low pH value produced large grain size and better ferromagnetic features. The ferromagnetic properties of the material have been enhanced by lowering the pH value and increasing the annealing temperature. Mössbauer spectra provided insight of the local magnetic order, site occupancy of Ni and Fe ions and oxidation state of Fe ions in the spinel structure of Ni 1.5 Fe 1.5 O 4 ferrite. [ABSTRACT FROM AUTHOR]

Abstract: The compound α-Fe1.4Ga0.6O3 has been prepared by mechanical alloying of α-Fe2O3 and β-Ga2O3 and subsequent heating under vacuum condition. X-ray diffraction, Raman and Mössbauer spectroscopy confirmed stabilization of the material in rhombohedral phase. A remarkable change in the magnetic ordering has been found by substitution of non-magnetic Ga atoms in α-Fe2O3. The ferromagnetism in α-Fe1.4Ga0.6O3 is found to be more soft and enhanced in comparison to α-Fe2O3. The samples also exhibited features of exchange bias, low temperature surface paramagnetism, and suppression of Morin transition. Nano-sized grains and alloying process of the material affected these features up to certain extent. The results of magnetic measurements are highly interesting for designing metal doped α-Fe2O3 based ferromagnet for room temperature applications. [Copyright &y& Elsevier]

Highlights: [•] Nano-sized grains of Co1.5Fe1.5O4 ferrite have been prepared. [•] Structural, magnetic and dielectric properties have been studied. [•] Material exhibited ferromagnetism and giant permittivity. [•] Effect of interfacial heterogeneity has been demonstrated. [Copyright &y& Elsevier]

Highlights: [•] The ferrite Co3x Fe3(1−x)O4 has been synthesized by alloying Fe3O4 and Co3O4. [•] The correlation between structural phase and ferromagnetism has been studied. [•] The ferrite exhibited tunable ferromagnetic parameters with high squareness. [•] Unusual features, e.g., exchange bias, field controlled domain motion, studied. [•] The study is important for developing next generation magnetic ferrites. [ABSTRACT FROM AUTHOR]

Abstract: This work has been initiated with a curiosity to investigate the elemental composition and magnetic response of different grades of lead pencils (6B, 2B, HB, 2H, 5H) that people use in daily life. Interestingly, experimental results landed with a great achievement of observing soft magnetism in lead pencils, indicating a wide scope of magnetic tuning for room temperature applications. A novel magnetic composite has been synthesized by mixing different concentration of CoFe2O4 (CF) nanoparticles in 5H and 6B pencils for studying the magnetic tailoring aspects using pencils. Our results showed different possibilities of controlling disorder induced ferromagnetic parameters and a simple approach of producing sufficiently high coercive magnetic composite using pencils. [Copyright &y& Elsevier]

Abstract: The present work reports ferromagnetism by doping magnetic Mn atoms in the diamagnetic ZnO matrix and the ferromagnetism has been extended up to 640K in nano-grained Zn0.95Mn0.05O samples. The bulk and nano-grained samples were stabilized in hexagonal crystal structure with space group p63mc. The grain size and lattice strain of the samples were estimated from room temperature XRD spectrum. Surface morphology of the samples was examined at room temperature using SEM picture and EDX spectrum. The ferromagnetism of the bulk material shows enhancement in nano-grained samples, which was mainly due to the solution of Mn atoms into the lattice sites of ZnO by mechanical milling. The enhancement of magnetic moment and ferromagnetic ordering temperature with reduction in grain size has been understood in terms of the core–shell structure and existing theoretical models. The present work also demonstrated the role of surface spin disorder on the enhancement of ferromagnetism in Zn0.95Mn0.05O nanograins. [Copyright &y& Elsevier]

Abstract: We report enhancement of magnetization below the antiferromagnetic ordering temperature in nanoparticles of two antiferromagnets, viz CoRh2O4 and Cr2O3. The enhancement of magnetization below is systematic, being larger for sample with smaller particle size. Scaling analysis showed that such enhancement of magnetization in CoRh2O4 nanoparticles is due to the superparamagnetic type contribution of surface (shell) spins. The present work shows that similar analysis can also be applied in Cr2O3 nanoparticles. [Copyright &y& Elsevier]

Abstract: We discuss our investigation of DC magnetization, as a function of time, temperature and magnetic field, and explore some distinct magnetic behaviour in the polycrystalline spinel Co0.2Zn0.8Fe1.95Ho0.05O4. The system is essentially to be a ferrimagnet and the ferrimagnetic order (spontaneous magnetization) is identified using Arrot plot of data. Application of some scaling laws have shown the coexistence of spin glass (SG) and superparamagnetism (SPM) with ferrimagnetic order (FIMO) at low and high temperature, respectively, in the system. The coexistence of SG and SPM with FIMO shows paramagnetic to ferrimagnetic state at and ferrimagnetic to cluster spin glass state below . The non-linear increase, without hysteresis, of data above indicates the existence of short range interacting clusters in the paramagnetic state. In addition, the anisotropy effect of Ho3+ has shown some interesting magnetic features, such as, spin glass of Ising nature and an unusual maximum in the thermoremanent magnetization about 180K. [Copyright &y& Elsevier]