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  • 1
    Electronic Resource
    Electronic Resource
    A neutron scattering study of the quasi-one-dimensional, dilute Ising-like antiferromagnet CsCo0.83Mg0.17Br3 : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6451-6453 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Neutron scattering measurements have been performed on a single-crystal sample of CsCo0.83Mg0.17Br3, a quasi-one-dimensional, Ising-like antiferromagnet. Residual three- dimensional interactions between the dilute magnetic chains precipitate a phase transition to long-range order at TN∼9.0 K, and short-range correlations persist as high as 40 K. Relatively high-energy inelastic scattering from both "bulk'' spin-wave modes and "end'' modes is observed from the finite chains. The low-energy inelastic spectrum is dominated by soliton scattering due to antiphase domain walls propagating along the finite chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352630
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetic excitations in thulium metal (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 5283-5285 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed inelastic neutron scattering measurements on a single-crystal specimen of Tm at wave vectors κ=(1, 1,ζ) and (0,0,2+ζ) (ζ=0,...,1). Most of the measurements have been made at T=5 K, where Tm exhibits a seven-layer ferrimagnetic-antiphase-domain structure (four moments up, parallel to the c axis, followed by three moments down). At this temperature the excitation spectra consist of three peaks. The two lower energy excitations have been identified as originating from magnetovibrational scattering from the TA phonon, while the higher energy excitation is magnetic and exhibits only a weak dispersion (between 8.3 and 9.6 meV). At T=50 K, a temperature at which the system exhibits a c-axis sinusoidally modulated structure, the magnetic mode shows significant softening and broadening. The magnetovibrational scattering vanishes above the Néel temperature (TN=58.5 K) while the magnetic mode persists at least up to T=70 K. These results suggest that the Hamiltonian in this system is dominated by the crystal-field-anisotropy energy and that the exchange interaction is relatively weak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344637
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  • 3
    Electronic Resource
    Electronic Resource
    High-energy magnetic excitations in Mn90Cu10 : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6548-6550 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The study of the magnetic excitations in Mn-rich alloys should be a good test of the multiband calculations of the spin dynamics of pure γ-Mn, which is a prototypical itinerant-electron antiferromagnet. In this paper we report the results of recent neutron inelastic scattering measurements performed on Mn90Cu10 at room temperature (T=0.63TN) and up to 300 meV of energy transfer. These measurements were performed using the high-energy transfer (HET) chopper spectrometer at the ISIS spallation neutron source, Rutherford Appleton Laboratory, U.K. The results are in agreement with calculations using a model scattering function convoluted with the full HET resolution function. In this model there is a steep linear spin-wave dispersion (D≈250 meV A(ring)) for wave vectors up to ≈1/2 of the Brillouin zone and a strong damping which is linear in the wave vector q. For larger wave vectors the spin-wave energies are constant at about 190 meV. These features are qualitatively similar to the predictions of Cade and Young for pure γ-Mn.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352559
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  • 4
    Electronic Resource
    Electronic Resource
    Spin dynamics in a diluted Heisenberg NN antiferromagnet on a HCP lattice: Zn1−xMnxSe (abstract) : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5660-5660 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nature of magnetic excitations in disordered and short-range ordered antiferromagnetic systems continues to be an interesting problem. The family of AII1−xMnxBVI alloys (AII=Zn, Cd, Hg, BVI=S, Se, Te) offers highly interesting prototypes for such studies. In these systems, which crystallize in the zinc blende (ZB) or wurtzite structure, the Mn ions form, respectively, diluted FCC or HCP Heisenberg spin lattices with dominating nearest-neighbor AF coupling. Due to the strong frustration inherent in such lattices these systems do not exhibit long-range spin order even for Mn concentrations as high as x=0.70. Neutron scattering studies of spin dynamics in the zinc-blende forms (Zn1−xMnxTe and Cd1−xMnxTe) have been reported in a recent article.1 In the present paper we report the results of experiments on a wurtzite-type system, Zn1−xMnxSe, with x=0.55 and 0.40. As in the previous case of ZB alloys, the data reveal the existence of magnon-like modes that are extremely strongly damped, but still show a pronounced dispersive behavior. The range of static AF spin–spin correlations in Zn1−xMnxSe is extremely short (ξ=κ−1=5–15 A(ring)), and exhibits a significant anisotropy. The energy of the observed excitation is clearly correlated with ξ, i.e., it is higher in the Q-space directions for which the correlation range is longer. The results are discussed in the context of the existing theoretical models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353634
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  • 5
    Electronic Resource
    Electronic Resource
    Magnons in ferromagnetic terbium under high pressure : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6060-6062 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed an inelastic neutron scattering experiment in order to investigate the pressure dependence of the magnon dispersion of terbium in its ferromagnetic phase. Our measurements were performed along the crystal c axis at 90 K (well below the Curie temperature Tc=220 K) at ambient pressure, and at 4.3 and 15.2 kbar of applied hydrostatic pressure. The difference between the magnon dispersion curves at ambient pressure and at 4.3 kbar is small, while at 15.2 kbar the dispersion curve shifts appreciably towards higher energies. The measured magnon dispersion curves have been analyzed using a Hamiltonian that includes Heisenberg exchange as well as single-ion anisotropy terms. For each dispersion curve we have calculated five exchange constants and two anisotropy terms. The energy gap at q=0 due to the anisotropies is enhanced with pressure and exchange interactions acting between c planes appear to decrease with the application of high pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355457
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  • 6
    Electronic Resource
    Electronic Resource
    Separation of crystal-field levels and phonons in Pr dideuteride using polarized neutrons (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3423-3425 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polarized neutrons with polarization analysis are used for the first time successfully for distinguishing crystal-electric-field (CEF) excitations from phonons by investigating both the spin-flip and non-spin-flip cross sections. From this, it is shown that the 20 meV peak in Pr dideuteride, observed previously with unpolarized neutrons, arises from CEF excitations. Since this energy is nearly half the value of the CEF level at 41 meV known before, the 20 meV peak is composed of two contributions. At low temperatures it only arises from transitions from the ground state into the 20 meV level. At room temperature, on the other hand, the 20 meV level is thermally populated, so that transitions from the 20 meV into the 41 meV level are also obtained. This leads to the unexpected increase of the intensity of the 20 meV peak at increasing temperatures observed previously. The present result gives a strong contribution to the knowledge of the CEF parameters of the Pr3+ ions in PrD2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338971
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  • 7
    Electronic Resource
    Electronic Resource
    Polarized neutron measurement of "forbidden'' magnon scattering in Pt3Mn (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3751-3752 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have employed inelastic scattering of polarized neutrons to study the nature of the magnetic response in the vicinity of the Curie temperature (TC=493 K) for the intermetallic ferromagnet Pt3Mn. The measurements were taken on the HB-1 triple-axis spectrometer at ORNL, with a field of 10 kOe applied along the scattering vector Q. For 0.9TC 〈T〈1.2TC we observed underdamped magnons not only with the conventional (+) spin-wave polarization but also with the "forbidden" (−) polarization, with an intensity difference I(+)−I(−) which is approximately proportional to the magnetization. Both these observations are in agreement with the slowly fluctuating spin-density theory of itinerant ferromagnetism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334960
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  • 8
    Electronic Resource
    Electronic Resource
    Nuclear spin ordering observed by neutron diffraction (invited) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 3784-3788 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A review is given of recent neutron scattering experiments which have been carried out at milli-Kelvin temperatures to study the hyperfine-enhanced nuclear-spin ordering in the singlet electronic ground state compounds PrSn3, PrCu2, and HoVO4. Bragg peaks were observed in PrSn3 which are due solely to the nuclear spin polarization of 141Pr caused by the hyperfine field from the antiferromagnetically ordered electronic moment. The temperature dependencies of the nuclear polarization and the additional electronic polarization induced by the nuclear polarization have been measured in detail. A magnetic phase transition in PrCu2 which is believed to correspond to a simultaneous ordering of both the nuclear and electronic spin systems has been observed at 58 mK. The positions of the magnetic diffraction peaks in reciprocal space are represented by G±τ, where G is a vector of the reciprocal lattice and τ=0.24a*±0.68c*, indicating that the magnetic periodicity is incommensurate with the chemical lattice. In HoVO4 magnetic diffraction peaks due to the antiferromagnetic ordering of the nuclear spin system were observed below 4.5 mK. The observed magnetic structure and the dependence of the neutron diffraction intensities on magnetic field are consistent with the predictions of Bleaney on the basis of dipolar energy considerations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334974
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  • 9
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    Lattice Dynamics of Lithium Fluoride (1968)
    American Physical Society
    Details
    Publication Date: 1968-04-15
    Print ISSN: 0031-899X
    Electronic ISSN: 1536-6065
    Topics: Physics
    Published by American Physical Society
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  • 10
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    Time-Resolved X-Ray Scattering Study of Ordering and Coarsening inCu3Au (1988)
    American Physical Society
    Details
    Publication Date: 1988-08-08
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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