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941.
942.
M. ElMassalami D. da S. OliveiraH. Takeya 《Journal of magnetism and magnetic materials》2011,323(16):2133-2136
Based on extensive Mossbauer effect (ME) and magnetization measurements, the orthorhombic AlFe2B2 was characterized as a ferromagnet (FM) because this character is evident as an onset of a FM transition at Tc=320 K and characteristic magnetizations isotherms below Tc. At liquid helium temperatures, the magnetization saturates to μsat≈1μB per Fe atom; a value which is half the one reported for the iron metal indicating a relatively more filled 3d band. The ME analysis revealed a hyperfine field H(0) of 88(2) kOe, an isomer shift (relative to Fe) of 0.50(2) mm/s, and a quadrupole parameter of 0.02 mm/s: all parameters extrapolated to zero Kelvin. The itinerant character of the magnetic moment will be discussed. 相似文献
943.
Sudhakar PandayB.S.S. Daniel P. Jeevanandam 《Journal of magnetism and magnetic materials》2011,323(17):2271-2280
Nanocrystalline Co-Ni alloys with different compositions were prepared by polyol reduction of mixed cobalt nickel hydroxides. The precursors (mixed cobalt nickel hydroxides) were prepared by co-precipitation. Powder X-ray diffraction analysis indicated the formation of fcc phase in the alloys and their crystallite size in the range 17-25 nm. Scanning electron microscopy and transmission electron microscopy studies revealed the morphology of the particles as being close to spherical, and the energy dispersive X-ray analysis showed the stoichiometry of the alloys. The magnetization as a function of field and temperature of the alloys, measured using a superconducting quantum interference device, showed superparamagnetic behavior with negligible coercivity and remanence values. 相似文献
944.
Z.Q. Lv W.T. Fu S.H. Sun X.H. BaiY. Gao Z.H. Wang P. Jiang 《Journal of magnetism and magnetic materials》2011,323(7):915-919
Using the first-principles technique, the electronic structures, magnetic properties and phase stability of alloyed cementite with Cr or Mn were investigated. The calculations show that the chemical and mechanical stability of alloyed cementite can be strengthened by the use of Cr/Mn-doped method. The Magnetic Moments (Ms) of Mn1Fe2C, Mn2Fe1C, Cr1Fe2C and Cr2Fe1C are 5.274, 0.941, 1.864 and 0.736 μB/f.u, respectively. The Ms of Cr in Fe2CrC (−1.374 μB) and Cr2FeC (−0.032 μB) are different due to replacing different sites Fe atoms. The magnetic behaviors of Mn are different from Cr in alloyed cementite. The Ms of Mn in Fe2MnC and Mn2FeC are 2.300 μB and −0.147 μB, respectively. 相似文献
945.
U.P. Verma Sonu SharmaNisha Devi P.S. BishtP. Rajaram 《Journal of magnetism and magnetic materials》2011,323(5):394-399
We have investigated the structural, electronic and magnetic properties of the diluted magnetic semiconductor (DMS) Cd1−xMnxTe (for x=0.75 and 1.0) in the zinc blende (B3) phase by employing the ab-initio method. Calculations were performed by using the full potential linearized augmented plane wave plus local orbitals (FP-L/APW+lo) method within the frame work of spin-polarized density functional theory (SP-DFT). The electronic exchange-correlation energy is described by generalized gradient approximation (GGA). We have calculated the lattice parameters, bulk modulii and the first pressure derivatives of the bulk modulii, spin-polarized band structures, and total and local densities of states. We estimated the spin-exchange splitting energies Δx(d) and Δx(pd) produced by the Mn3d states, and we found that the effective potential for the minority spin is more attractive than that of the majority spin. We determine the s-d exchange constant N0α (conduction band) and p-d exchange constant N0β (valence band) and these somewhat agree with a typical magneto-optical experiment. The value of calculated magnetic moment per Mn impurity atom is found to be 4.08 μB for Cd0.25Mn0.75Te and 4.09 μB for Cd0.0Mn1.0Te. Moreover, we found that p-d hybridization reduces the local magnetic moment of Mn from its free space charge value of 5.0 μB and produces small local magnetic moments on the nonmagnetic Cd and Te sites. 相似文献
946.
L.B. Drissi A. Benyoussef E.H. Saidi M. Bousmina 《Journal of magnetism and magnetic materials》2011,323(23):3001-3006
The magnetic properties of Mn-doped ZnO semiconductor have been investigated using the Monte Carlo method within the Ising model. The temperature dependences of the spontaneous magnetization, specific heat and magnetic susceptibility have been constructed for different concentrations of magnetic dopant Mn and different carrier concentrations. The exact values of Mn concentration and carrier concentration at which high temperature transition occurs are determined. An alternative for the explanation of some controversies concerning the existence and the nature of magnetism in Mn diluted in ZnO systems is given. Other features are also studied. 相似文献
947.
Yu.D. Zavorotnev L.I. MedvedevaB.M. Todris E.A. DvornikovO.Yu. Popova 《Journal of magnetism and magnetic materials》2011,323(22):2808-2812
Experimental data on magnetization of the antiferromagnetic (AFM) polycrystalline samples in the temperature range of 20-300 K, for pressures of 2 kbar and in magnetic field of 300 kOe, are presented in the paper. In the fields of 250 kOe, the magnetization curve demonstrates a jump explained by exchange-interaction sign change. In the region of 50-70 kOe, on the differential susceptibility versus magnetic field curve, there is a break of the 2nd order corresponding to the anomalous behavior of the magnetization. The obtained results were processed on the basis of the phenomenological Landau theory. It is shown that the ferromagnetic vector occurrence is forced during the formation of AFM spiral structure. The behavior of thermodynamic potential factors has been determined. Three more anomalies have been revealed and explained by a jump-like magnetization change of the Co-subsystem. 相似文献
948.
E. De FazioP.G. Bercoff S.E. Jacobo 《Journal of magnetism and magnetic materials》2011,323(22):2813-2817
Polycrystalline manganese-zinc ferrite with lithium substitution of composition Li0.5xMn0.4Zn0.6−xFe2+0.5xO4 (0.0≤x≤0.4) was prepared by the usual ceramic method. X-ray diffraction analysis confirmed that the samples have a spinel structure and are of single phase for some values of Li content. Lithium doping considerably modifies saturation magnetization since its value increases from 57.5 emu/g for x=0.0 to 82.9 emu/g for x=0.4. Lithium inclusion increases the real permeability (over 1 MHz) while the natural resonance frequency shifts to lower values as the fraction of Li increases. These ferrites show good electromagnetic properties as absorbers in the microwave range of 1 MHz - 1 GHz. 相似文献
949.
Tunnel magnetoresistance in alumina, magnesia and composite tunnel barrier magnetic tunnel junctions
Oliver SchebaumVolker Drewello Alexander AugeGünter Reiss Markus MünzenbergHenning Schuhmann Michael SeibtAndy Thomas 《Journal of magnetism and magnetic materials》2011,323(11):1525-1528
Using magnetron sputtering, we have prepared Co-Fe-B/tunnel barrier/Co-Fe-B magnetic tunnel junctions with tunnel barriers consisting of alumina, magnesia, and magnesia-alumina bilayer systems. The highest tunnel magnetoresistance ratios we found were 73% for alumina and 323% for magnesia-based tunnel junctions. Additionally, tunnel junctions with a unified layer stack were prepared for the three different barriers. In these systems, the tunnel magnetoresistance ratios at optimum annealing temperatures were found to be 65% for alumina, 173% for magnesia, and 78% for the composite tunnel barriers. The similar tunnel magnetoresistance ratios of the tunnel junctions containing alumina provide evidence that coherent tunneling is suppressed by the alumina layer in the composite tunnel barrier. 相似文献
950.
Sandhya DwevediG. Markandeyulu P.R. OhodnickiAlex Leary M.E. McHenry 《Journal of magnetism and magnetic materials》2011,323(15):1929-1933
A systematic investigation of the influence of different types of annealing on the magnetoimpedance (MI) effect in melt-spun (Co1−xFex)89Zr7B4 [x=0, 0.025, 0.05] and (Co0.88Fe0.12)78.4Nb2.6Si9B9Al ribbons has been carried out in the frequency range 500 kHz-13 MHz and under dc magnetic fields (Hdc) up to 80 Oe. In the stress annealed ribbons, the strain-induced transverse anisotropy is seen to result in large MI. Magnetic domains were investigated in the ribbons through magnetic force microscopy. 相似文献