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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7139-7141 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature dependence of magnetism in the vicinity of the ferromagnetic instability point of amorphous Fe has been investigated on the basis of the finite temperature theory of amorphous metallic magnetism which takes into account the transverse spin degrees of freedom. The theory is based on the functional integral technique to the degenerate-band Hubbard Hamiltonian and the distribution function method for local magnetic moments with structural disorder. Numerical calculations have been performed with decreasing temperature near the boundary between the ferromagnetic and the spin glass phases. It is shown that the amorphous metals around Fe exhibit the transition from the collinear to the noncollinear ferromagnetic state at a temperature lower than the Curie temperature, due to the freezing of transverse spin components. The present results are consistent with those of recent Mössbauer measurements on Fe-rich amorphous transition metal alloys. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 3265-3273 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic properties of Fe and Ni have been investigated on the basis of the theory of metallic magnetism which interpolates between crystals and amorphous structures using the average coordination number z* and the fluctuation of interatomic distance Δ. Calculated magnetic phase diagram of Fe is shown to consist of three phases on the z*−Δ plane: the ferromagnetism (F) in the region z*(approximately-less-than)10.5, the spin glass (SG) in the region z*(approximately-greater-than)10.5, and the paramagnetism (P) around z*=11.0 and Δ=0.0. In the region F, the magnetization and the Curie temperature are weakened with increasing z*, while they are considerably enhanced with increasing Δ. The phase diagram explains the ferromagnetism of amorphous Fe powder and the SG in amorphous Fe containing early transition metals. In the case of Ni, F and P are found. In the region F the magnetization first decreases and tends to become constant with increasing Δ. The Curie temperature also decreases but shows a minimum as a function of Δ. Both of them are found to be smaller than those of fcc Ni, and to be sensitive to the degree of structural disorder. This explains qualitatively the nonunique magnetism of amorphous Ni in experiment. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3426-3432 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetic properties of amorphous FecNi1−c alloys are investigated on the basis of a single-site theory which combines the geometrical-mean model for the electronic structure calculations of amorphous alloys with the finite-temperature theory of metallic magnetism. Numerical results for magnetization versus concentration curves show strong ferromagnetism in the region 0.1(approximately-less-than)c(approximately-less-than)0.8. This explains the recent experimental finding of large hyperfine fields for amorphous FecNi1−c alloys in the Invar concentration region. The calculated Curie temperatures for amorphous structure show a shift of the maximum Curie temperature toward higher Fe concentration, which is in qualitative agreement with the experimental data of amorphous (Fe-Ni)90Zr10 alloys. It is demonstrated that such behavior is caused by a change of electronic structure due to structural disorder rather than by simple volume expansion; at around 60 at. % Fe, the main peak of the nonmagnetic density of states of the amorphous alloy shifts to an energy lower than that of the crystalline fcc counterpart so that the Fermi level is at the main peak, leading to a large magnetic energy gain. The agreement between calculated concentration dependence of effective Bohr magneton numbers and the experimental data for liquid alloys also supports this theory.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3862-3864 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A molecular dynamics method which allows us to determine the magnetic structures of itinerant magnets with a few hundred atoms in a unit cell has been developed on the basis of the functional integral method. The method yields the generalized Hartree–Fock approximation at the ground state, and describes the finite temperature magnetism accompanied by the second order phase transition. The results for fcc transition metals with the use of 108 atoms in a unit cell show a complex antiferromagnetic (AF) structure for the d electron number nd=6.0, the first-kind AF for nd=6.2, the helical structure with Q=(0,1/3,1)2π/a for nd=6.4, the helical structure with the same Q but with modulated amplitudes of local moments for nd=6.6. A helical structure with Q=(0,1/3,2/3)2π/a is obtained for γ-Fe. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3859-3861 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Noncollinear magnetism in the vicinity of amorphous Fe has been investigated by developing the finite temperature theory of amorphous metallic magnetism which takes into account the transverse spin fluctuations. The theory is based on the functional integral technique to the degenerate-band Hubbard Hamiltonian with Hund's rule coupling and the distribution function method for local magnetic moments with structural disorder. It is shown that an isotropic spin-glass is realized in amorphous Fe, by taking into account the transverse components of local magnetic moments. The origin of the spin-glass around amorphous Fe is explained by the nonlinear magnetic couplings between Fe local moments and the local environment effects on the amplitude of Fe local moments. When the d electron number N is increased, the isotropic spin-glass changes to a noncollinear ferromagnet at N=7.40 and finally changes to a collinear ferromagnet beyond N=7.47 at 35 K. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 32 (2005), S. 0 
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  This study evaluates the bonding characteristics of a lithium disilicate-based ceramic material (IPS Empress 2). Two sizes of disk specimens of the material were made, and three groups of disk pairs were separately surface-prepared using three techniques; etching with phosphoric acid, etching with hydrofluoric acid, and air-abrasion with alumina. Each group was further divided into four sub-groups; group (i) was bonded with the Variolink II composite, (ii) was treated with the Monobond-S silane primer and bonded with the Variolink II composite, (iii) was bonded with the Super-Bond acrylic adhesive and (iv) was treated with the Porcelain Liner M silane primer and bonded with the Super-Bond acrylic adhesive. Shear bond strengths were determined before and after 100 000 thermocycles. Bond strength varied from 10·6 to 71·5 MPa before thermocycling, whereas post-thermocycling bond strength ranged from 0 to 61·2 MPa. Among the three surface preparations, hydrofluoric acid etching (HF) was most effective in enhancing bond strength of both luting materials, especially for unsilanized specimens. Application of the silane primer elevated bond strength of both luting agents regardless of surface preparation method. It can be concluded, for both luting agents, that durable bond to the Empress 2 ceramic material can be achieved through the combined application of HF and the proprietary silane primer.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 104-107 (1992), S. 91-92 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 54-57 (1986), S. 1231-1232 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 104-107 (1992), S. 677-678 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 66 (1987), S. L163-L166 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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