[en] A review is given of selected neutron scattering results on 1D and 2D magnets using elastic, quasi-elastic and inelastic neutron scattering techniques. We discuss for 2D systems critical properties of the 2D Ising antiferromagnets K₂CoF₄ and Rb₂CoF₄; the percolation problem and the excitations in diluted 2D Ising antiferromagnets. For 1D systems we discuss the validity and failure of linear spin wave theory for excitation in short-range ordered systems; nonlinear spin dynamics: theory and experimental evidence in CsNiF₃. (orig.)

[en] A simple analysis of the inelastic neutron low energy peak recently observed in liquid ³He allows to extract a value for the spin-spin interaction close to 1, reinforcing the paramagnon model hypothesis which assumes liquid ³He to be close to become magnetic. Further experiments at finite pressure are suggested. (orig.)

[en] The magnetic phase diagram of ErB₄ was studied on a single crystal by neutron diffraction in the temperature range of 4.2 to 17 K with outer magnetic fields up to 70 kOe. The H-T phase diagram shows three magnetic phases (antiferromagnetic, ferrimagnetic and ferro-paramagnetic) and a triple point at Tsub(t) = (11.7 +- 0.2) K and Hsub(t) = (21 +- 2) kOe. (orig.)

[en] This paper summarizes the present status of neutron scattering studies on the itinerant electron system with emphasis on the magnetic excitations in the quasi-localized spin system. After describing the characteristics of the spin dynamics in two extreme cases of localized spin sytems (Heusler alloys) and of weak itinerant ferromagnet (MnSi), the recent experimental results obtained for typical quasi-localized spin systems, Ni, FePt₃ and MnPt₃, and Invar alloys: Fe₆₅Ni and Fe₃Pt are discussed. (orig.)

[en] Quasi-elastic neutron scattering experiments have been performed on the one-dimensional antiferromagnet (CD₃)₄NMnCl₃ (TMMC) at low temperature, 1 < T < 10 K, in the presence of a magnetic field, 0 < H < 40 kOe. Our results show that in zero field TMMC is in an XY state for T approx. 5 K. In a field applied along a direction, perpendicular to the chain axis, TMMC undergoes an XY-Ising crossover transitions. (orig.)

[en] The spin correlation between two-dimensionally (2D) ordered antiferromagnetic layers in the random antiferromagnets Rb₂Cosub(c)Mgsub(1-c)F₄ depends strongly on the rate at which the sample is cooled through the Neel point Tsub(N) and decreases markedly with decreasing Co²⁺ ion concentration c. Preliminary data are presented which indicate that the order below sub(N) is metastable and relaxes to a fully correlated 3D ordered state on a finite, measurable, time-scale. (orig.)

[en] By means of elastic neutron scattering on single-crystal and powder samples of HoP the temperature dependence of magnetic structures and order parameters was determined. At Tsub(t) = (4.7 +- 0.1) K the flopside configuration transforms abruptly to a ferromagnetic state with Tsub(c) = (5.6 +- 0.1) K. Schottky defects tend to short-range magnetic order. (orig.)

[en] Measurements of the magnetic response of an unalloyed chromium crystal as a function of temperature show changes which are consistent with the introduction of a band gap below 301 K in the ISDW regime. In general the behaviour is difficult to reconcile with current theoretical expectations. (orig.)

[en] Polarized neutron diffraction measurements have been done on CoMnP single crystals at room temperature. The magnetic moments on the tetrahedral Cosup(I) and pyramidal Mnsup(II) atoms are 0.06sub(μB) and 2.66sub(μB), respectively. The observed magnetic form factor suggests that the unpaired 3d-electrons are quasi-localized on the atoms. (orig.)

[en] The results of polarized neutron elastic diffuse scattering measurements on dilute iron-based alloys with V, Cr and Mn impurities are presented. The observed values of impuritiy moments in the dilute limit agree well with theoretical calculations of Campbell and Gomes and support the idea of the existence of isolated impurity states in these alloys. (orig.)