Showing papers by "S. M. Yusuf published in 2016"
TL;DR: A series of Ni x Zn 1− x Fe 2 O 4 (x = 0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties as mentioned in this paper.
65 citations
TL;DR: In this paper, the structural, magnetic and electrical properties of nanocrystalline particles of Zr and Co for Fe have been investigated in a wide temperature range of 500-1100°C.
53 citations
TL;DR: In this article, the structural, magnetic, and thermodynamic properties of the double perovskite compound (La) were reported from x-ray, neutron diffraction, neutron depolarization, and nuclear magnetic resonance (NMR) measurements.
Abstract: We report the structural, magnetic, and thermodynamic properties of the double perovskite compound ${\mathrm{La}}_{2}{\mathrm{CuIrO}}_{6}$ from x-ray, neutron diffraction, neutron depolarization, $\mathit{dc}$ magnetization, $\mathit{ac}$ susceptibility, specific heat, muon-spin-relaxation $(\ensuremath{\mu}\mathrm{SR})$, electron-spin-resonance (ESR) and nuclear magnetic resonance (NMR) measurements. Below $\ensuremath{\sim}113$ K, short-range spin-spin correlations occur within the ${\mathrm{Cu}}^{2+}$ sublattice. With decreasing temperature, the ${\mathrm{Ir}}^{4+}$ sublattice is progressively involved in the correlation process. Below $T=74$ K, the magnetic sublattices of Cu (spin $\mathit{s}=\frac{1}{2}$) and Ir (pseudospin $\mathit{j}=\frac{1}{2}$) in ${\mathrm{La}}_{2}{\mathrm{CuIrO}}_{6}$ are strongly coupled and exhibit an antiferromagnetic phase transition into a noncollinear magnetic structure accompanied by a small uncompensated transverse moment. A weak anomaly in $\mathit{ac}$ susceptibility as well as in the NMR and $\ensuremath{\mu}\mathrm{SR}$ spin lattice relaxation rates at 54 K is interpreted as a cooperative ordering of the transverse moments which is influenced by the strong spin-orbit coupled $5\mathit{d}$ ion ${\mathrm{Ir}}^{4+}$. We argue that the rich magnetic behavior observed in ${\mathrm{La}}_{2}{\mathrm{CuIrO}}_{6}$ is related to complex magnetic interactions between the strongly correlated spin-only $3\mathit{d}$ ions with the strongly spin-orbit coupled $5\mathit{d}$ transition ions where a combination of the spin-orbit coupling and the low symmetry of the crystal lattice plays a special role for the spin structure in the magnetically ordered state.
40 citations
TL;DR: In this paper, a co-precipitation technique was used to synthesize polycrystalline nanoferrites with chemical formula MgxZn1−xFe2O4 (x=0.5, 0.6 and 0.7) and they were subsequently heated to 800°C in order to investigate structural, thermal and magnetic properties.
36 citations
TL;DR: In this article, the preparation of monophasic Zr-substituted magnetite (Zr x Fe 3− x O 4 ; 0≤ x ≤ 1) nanoparticles by wet chemical route is reported.
33 citations
TL;DR: In this article, the structural and magnetic properties of thermal plasma synthesized Fe 1− x Ni x (x ǫ = 0.25, 0.33,0.67 and 0.75) alloy nanoparticles have been investigated using x-ray diffraction, neutron diffraction and transmission electron microscopy techniques.
27 citations
TL;DR: In this paper, the structural and magnetic behavior of Hf x Fe 3− x O 4 (0.8) magnetic nanoparticles are reported. But, the properties of these nanoparticles were not investigated.
16 citations
TL;DR: In this paper, a solid state reaction method was used to obtain polycrystalline samples of Ga 1− x Sc x FeO 3 (x = 0, 0.1, 0., 0.2, and 0.3) and they were found to crystallize in the orthorhombic space group Pna2 1.
12 citations
24 Feb 2016
TL;DR: In this article, the microscopic origin of temperature and magnetic-field actuated magnetization reversal in Cu073Mn077[Fe(CN)6]zH2O, using XMCD was investigated.
Abstract: We have investigated the microscopic origin of temperature and magnetic-field actuated magnetization reversal in Cu073Mn077[Fe(CN)6]zH2O, using XMCD Our results show a fair deviation from the mean-field-theory in the form of different ordering temperatures of Fe and Mn sublattices A preferential sign reversal of Mn spin under magnetic field and different spin cant angles for the two sublattices have also been observed An antiferromagnetic coupling between the Fe and Mn sublattices along with different ordering temperatures (sublattice decoupling) for these sublattices explain the temperature-dependent magnetization reversal Whereas, Mn spin reversal alone (under external magnetic field) is responsible for the observed field-dependent magnetization reversal The dissimilar magnetic behavior of Fe and Mn sublattices in this cubic 3d-orbital system has been understood by invoking disparity and competition among inter-sublattice magnetic control parameters, viz magnetic Zeeman energy, exchange coupling constant and magnetic anisotropy constant Our results have significant design implications for future magnetic switches, by optimizing the competition among these magnetic control parameters
8 citations
TL;DR: In this paper, an increase in the relative extent of ferromagnetic domains compared to paramagnetic domains in Ni 0.50 Fe 0.25 Alloy is attributed to increase in particle size brought about by the high temperature activation prior to hydrogenation.
7 citations
23 May 2016
TL;DR: In this paper, a co-precipitation method was used to synthesize nanoparticles of Mg0.5Zn0.4 ferrite by employing core-shell model and cation redistribution.
Abstract: Nanoparticles of Mg0.5Zn0.5Fe2O4 ferrite have been synthesized by co-precipitation method. XRD and Mossbauer spectroscopic results of Mg0.5Zn0.5Fe2O4 annealed at 200 °C, 500 °C and 800 °C are reported. It was observed that the crystallite size increases and the lattice parameter decreases with increase in annealing temperature. The observed decrease in lattice strain supports the increase in crystallite size. The Mossbauer spectra of the samples annealed at 200 °C and 500 °C exhibits superparamagnetic doublets whereas the Mossbauer spectrum of the sample annealed at 800 °C exhibits paramagnetic doublet along with weak sextet of hyperfine interaction. The values of isomer shift resemble the presence of high spin iron ions. The studied ferrite nanoparticles are suitable for biomedical applications. The results are incorporated employing core-shell model and cation redistribution.Nanoparticles of Mg0.5Zn0.5Fe2O4 ferrite have been synthesized by co-precipitation method. XRD and Mossbauer spectroscopic results of Mg0.5Zn0.5Fe2O4 annealed at 200 °C, 500 °C and 800 °C are reported. It was observed that the crystallite size increases and the lattice parameter decreases with increase in annealing temperature. The observed decrease in lattice strain supports the increase in crystallite size. The Mossbauer spectra of the samples annealed at 200 °C and 500 °C exhibits superparamagnetic doublets whereas the Mossbauer spectrum of the sample annealed at 800 °C exhibits paramagnetic doublet along with weak sextet of hyperfine interaction. The values of isomer shift resemble the presence of high spin iron ions. The studied ferrite nanoparticles are suitable for biomedical applications. The results are incorporated employing core-shell model and cation redistribution.
TL;DR: In this paper, the results of an electronic structure study on NixCu1−xMnSb Heusler alloys, using Mn-2p core-level photoemission spectroscopy, were presented.
Abstract: The electronic structure of Heusler alloys having mixed magnetic phases, comprising of vicinal anti-ferromagnetic and ferromagnetic orders, is of great significance. We present the results of an electronic structure study on NixCu1−xMnSb Heusler alloys, using Mn-2p core-level photoemission spectroscopy. Room temperature data in the paramagnetic phase reveal a non-monotonic variation of both electron correlation strength and conduction-band hybridization such that the former enhances while the latter weakens for compositions showing a mixed phase relative to compositions at the phase boundaries to the ordered phases. The results suggest a possible electronic driving force for settling mixed-magnetic phases.
TL;DR: Signatures of coupling between magnetic and electric order parameters were revealed by pyrocurrent measurements carried out in presence of magnetic fields.
Abstract: We report the synthesis and electric properties of nano-crystalline Tb1-xYxMnO3 (x = 0, 0.1, 0.2, 0.3 and 0.4) compounds prepared by gel-combustion method. These samples were characterized by a number of techniques including X-ray diffraction (XRD), Raman spectroscopy, specific-heat measurement, neutron diffraction, and magnetic field dependent pyrocurrent measurement. All the samples crystallize in the orthorhombic structure with space group Pnma at room temperature. Anomalies were observed in low temperature specific-heat measurement corresponding to magnetic and electric phase transitions. The magnetic phase transitions occurred at ~35, ~22-28 and ~7 K for all the samples. Signatures of coupling between magnetic and electric order parameters were revealed by pyrocurrent measurements carried out in presence of magnetic fields.