Showing papers on "Magnetic structure published in 1984"
TL;DR: In this article, a martensitic phase transition to a complex tetragonal structure occurs on cooling below 202 K. Reasons for the structural transformation are discussed, and details of the low temperature crystallographic superlattice and magnetic structure are determined.
Abstract: Magnetization, magnetic susceptibility, optical microscopy, X-ray diffraction and neutron diffraction measurements have been made on a quenched sample of Ni2MnGa. Room-temperature neutron diffraction patterns indicate a highly ordered Heusler alloy, L21 type, structure. The alloy is ferromagnetic with a Curie temperature of 376 K, and a magnetic moment of 4·17μB largely confined to the Mn sites, but probably with a small moment <07·3μB associated with the Ni sites. A martensitic phase transition to a complex tetragonal structure occurs on cooling below 202 K. Neutron diffraction oscillation photographs taken using the D12 facility at Institut Laue Langevin, Grenoble, and low-temperature powder neutron diffraction data enabled details of the low temperature crystallographic superlattice and magnetic structure to be determined. Reasons for the structural transformation are discussed.
1,048 citations
TL;DR: In this article, the crystal structure of the ordered, distorted perovskite Sr2YRuO6 was refined using time-of-flight powder neutron diffraction data.
141 citations
TL;DR: In this paper, the connection between electronic structure and ferromagnetism is studied for the Fe-Co alloy system by means of self-consistent local spin-density functional calculations.
Abstract: The connection between electronic structure and ferromagnetism is studied for the Fe-Co alloy system by means of self-consistent local spin-density functional calculations. The local environment of these BCC-substitutional alloys is modelled by different ordered compounds: besides BCC Co and Fe these are Co3Fe and Fe3Co in the Fe3Al structure and FeCo in the CsCl and NaTl structures. FeCo in the CsCl structure is studied in great detail giving the ferromagnetic band structure, decomposed state densities, Wigner delay times and the spatial form of the spin density. The role of the nearest-neighbour coordination in determining the value of the magnetic moments is discussed for all the compounds studied. The calculated and measured magnetic moments are compared and trends are analysed and explained.
125 citations
TL;DR: In this paper, the magnetic ordering of polycrystalline samples of (Pr, Nd, Gd, Tb, Dy, Er)Ru2Si2 compounds was investigated in the temperature range between 1.8 and 293 K.
81 citations
TL;DR: In this paper, the ternary compounds TbRH2Si2 and CeRh 2Si2 with a tetragonal structure have been studied and a wave vector k=[ 1 2 1 2 0] in which the coupling within a plane is antiferromagnetic.
75 citations
TL;DR: In this paper, the composition and temperature dependence of the magnetic anisotropy energy is studied by analysing the approach to saturation of isothermal magnetization as well as by using the singular point detection method.
60 citations
TL;DR: In this article, profile analysis of constant-wavelength powder neutron diffraction data has been used to refine the crystal structure of the ordered perovskite Ca2YRuO6.
54 citations
TL;DR: In this article, the magnetic structure of holmium has been studied by neutron diffraction techniques and the magnetic form factor has been measured and compared with relativistic atomic calculations, and evidence for asphericity in the magnetization density is presented and discussed.
Abstract: The magnetic structure of high purity single crystals of holmium has been studied by neutron diffraction techniques. Although the general characteristics of the magnetic structure have been found to agree with earlier measurements, some discrepancies have been resolved and new features have been observed. The magnetic form factor has been measured and compared with relativistic atomic calculations. The low temperature structure (T<20 K) is that of a conical ferromagnet with wave vector (1/6)(2π/c) along the c axis. The basal plane moment is 9.7 μB and the c‐axis ferromagnetic component is 1.6 μB at T=6 K. Bunching of the basal plane moments around the easy hexagonal direction has been observed below T=50 K. Evidence for asphericity in the magnetization density is presented and discussed. The wave vector of the basal plane modulation decreases monotonically with temperature in general accordance with the Elliott–Wedgewood theory. Several inflection points were observed, however, which correspond to commens...
47 citations
TL;DR: Maintien de l'ordre antiferromagnetique au voisinage des amas de defauts, avec modifications de la direction de spin, d'apres les mesures de diffraction de neutrons a 45 K (structure de spin a peu pres colineaire au niveau local) as discussed by the authors.
Abstract: Maintien de l'ordre antiferromagnetique au voisinage des amas de defauts, avec modifications de la direction de spin, d'apres les mesures de diffraction de neutrons a 45 K (structure de spin a peu pres colineaire au niveau local). Analyse des spectres Mossbauer tres complexes (a 4,2 et 78 K): un sextriplet hyperfin de Fe(III), deux sextriplets hyperfins de Fe(II), un doublet quadripolaire de Fe(III)
47 citations
TL;DR: In this paper, the magnetically induced tetragonal lattice distortion observed in an antiferromagnetic metal, γMn, was studied using a total energy local spin density band theory approach.
47 citations
TL;DR: An extensive investigation of the system MnAs1−xPx for x = 0.18 has been carried out with a series of methods as discussed by the authors, including magnetic susceptibility, magnetization, resistivity and Hall resistance measurements as well as neuron and X-ray diffraction.
TL;DR: In this paper, a series of neutron experiments on stoichiometric PrO 2 have been conducted at the Intense Pulsed Neutron Source, Argonne National Laboratory, which has the cubic CaF 2 structure, orders antiferromagnetically at 14 K with a type I magnetic structure.
TL;DR: In this article, a method to grow single ammonium vanadate (IV, V) (NH 4 ) 2 V 3 O 8 has been devised and the crystal structure is tetragonal P4bm; residual factor is R = 0.030.
TL;DR: In this article, measurements of magnetisation, resistivity and magnetoresistivity have been made on polycrystalline Gd2 in the case of the metamagnetic phase, which provides indirect evidence for superzones and a spiral magnetic structure.
Abstract: Measurements of the magnetisation, resistivity and magnetoresistivity have been made on polycrystalline Gd2In The compound orders as a metamagnet below 995K but shows ferromagnetic order between 995 and 187K The electrical resistivity reflects both transitions In the case of the metamagnetic phase it provides indirect evidence for superzones and a spiral magnetic structure
TL;DR: The umbrella magnetic structure of the terbium iron garnet (TbIG) has been studied using neutron diffraction experiments performed in the 4.2 to 650 K temperature range.
Abstract: The umbrella magnetic structure of the terbium iron garnet (TbIG) has been studied using neutron diffraction experiments performed in the 4.2 to 650 K temperature range which covers both the Neel temperature (T N = 550 ± 10 K) and the compensation temperature (T comp = 244 ± 2 K). When T> T N , the observed peak intensities originate from nuclear contribution only. When T comp N , the results have been interpreted in the Neel theory of ferrimagnetism. Below T comp , three salient features have been observed : there appear superstructure lines forbiden by the cubic space group Ia3d, such as
TL;DR: In this paper, the antiferromagnetic collinear structure of polycrystalline compounds ErMn 2 Si 2 (ErMn2 Si 2, Ermn 2 Ge 2 and ErFe 2 Si2 ) was studied in the temperature range between 1.8 and 293 K.
TL;DR: In this paper, the divalent thulium compound TmTe was used for magnetic structure determination, which leads to a type II antiferromagnet below the Neel temperature T N =.43 K. No crystal field excitations were observed.
TL;DR: The crystal and magnetic structures of ilvaite Ca(Fe2+, Fe3+)Fe2+Si2O7O(OH) have been obtained by profile refinement of high resolution neutron powder data from a natural sample from Seriphos, Greece as mentioned in this paper.
Abstract: The crystal and magnetic structures of ilvaite Ca(Fe2+, Fe3+)Fe2+Si2O7O(OH) have been obtained by profile refinement of high resolution neutron powder data from a natural sample from Seriphos, Greece. Below about 400 K an electronic transition from an itinerant to an ordered state is expected, with the structure changing from orthorhombic to monoclinic. The structure remains monoclinic P2
1/a down to 5 K, with Fe2+ almost completely ordered on one of the A-sites and Fe3+ on the other: the ordering may increase with decreasing temperature. The B-site contains Fe2+ plus a small amount of Mn2+ impurity. There are two magnetic transitions, at 116 K and 40 K: at 80 K the Fe2+ and Fe3+ spins on the A-sites along one infinite c-axis chain are parallel, and antiparallel to those along the adjoined edge-sharing centrosymmetrically related chain. The spin vectors are all perpendicular to the plane of these chains, i.e. almost parallel to the crystallographic b-axis. At 5 K, this order is maintained, but the Fe2+ spins on the B-sites order antiferromagnetically as well, again almost along the b-axis. These results explain the earlier Mossbauer and magnetisation measurements.
TL;DR: In this article, the crystal and magnetic structure of the hard magnetic alloy Mn1.074Al0.005, which has a body centered tetragonal structure, has been investigated.
Abstract: The crystal and magnetic structure of the hard magnetic alloy Mn1.074Al0.871C0.005, which has a body centered tetragonal structure, has been investigated. Neutron diffraction data shows that Mn0.992, C0.008 occupy the (0,0,0) site and Mn0.082, Al0.871, C0.047 occupy the ( 1/2 , 1/2 , 1/2 ) site. The magnetic moments of manganese atoms are along the c axis, pointing in opposite directions for the two sites. Comparing these results with those of Mn1.09Al0.91, the significant improvement of magnetic and mechanical properties in the ternary alloy MnAlC is explained.
TL;DR: In this paper, a neutron diffraction experiment on the hyperfine enhanced nuclear spin system of HoVO4 has been carried out following adiabatic demagnetization cooling, and the results are consistent with the magnetic structural model proposed by Bleaney on the basis of dipolar energy considerations.
TL;DR: The magnetic structure of the hexagonal polymorph of FeGe has been investigated by means of neutron diffraction on single crystals at low temperature and for magnetic fields applied perpendicular to the c axis.
Abstract: The magnetic structure of the hexagonal polymorph of FeGe has been investigated by means of neutron diffraction on single crystals at low temperature and for magnetic fields applied perpendicular to the c axis. Between 410 and approximately 55K the magnetic structure is collinear c-axis antiferromagnetic. Below approximately 55K the structure changes to c-axis double-cone antiferromagnetic with an inter-layer turn angle for the basal-plane moment component of 194.4 degrees , independent of temperature and applied field. The cone half-angle increases with decreasing temperature to approximately 14 degrees at 4.2K, but its temperature dependence shows a pronounced kink at 30K, indicating a phase change at this temperature. At 4.2K the authors observe an anomalous decrease of the basal-plane moment component at a critical field (B perpendicular to c) of 1.4 T. As the temperature is increased the critical field decreases and the anomaly becomes less pronounced. The cone structure is found to persist up at least 3.9 T, which was the upper limit of the applied field. The neutron diffraction data are discussed and related to previously published macroscopic data (e.g. magnetic susceptibility, torsion and Mossbauer data) as well as to earlier neutron diffraction results.
TL;DR: In this paper, a coherent analysis of the complex magnetization processes for magnetic fields applied along the three main crystallographic directions is proposed, and it is shown unambiguously that the magnetic structure of DyCu is of the triple-q type.
TL;DR: In this paper, a Monte Carlo study of a hexagonal Ising antiferromagnet reveals the occurrence of a new type of modulated phase in which a spin structure described by using three sublattices is randomly modulated in the lattice.
Abstract: A Monte Carlo study of a hexagonal Ising Antiferromagnet reveals the occurrence of a new type of modulated phase in which a spin structure described by using three sublattices is randomly modulated in the lattice. The order parameter of this phase is not individual sublattice magnetizations but a symmetric function of them which corresponds to the magnetic structure factor F (1/3, 1/3, 0). As the temperature is decreased, this phase gradually changes into a usual homogeneous ferrimagnetic phase. This process is discussed in detail. It is suggested that this modulated phase occurs in CsCoCl 3 and CsCoBr 3 .
TL;DR: In this article, the spin dynamics of the cerium and uranium monopnictides studied by diffuse and inelastic neutron scattering is reviewed, where the spin wave dispersion is split into two modes of transverse polarization due to the exchange anisotropy.
Abstract: The spin dynamics of the cerium and uranium monopnictides studied by diffuse and inelastic neutron scattering is reviewed. The diffuse scattering above the antiferromagnetic ordering temperature largely corresponds to longitudinal spin fluctuations which are highly anisotropic. For CeAs, CeSb, and UAs multicritical behavior has been found, i.e., the symmetry of the critical scattering above TN differs from the actual type of magnetic ordering below TN. In the ordered state the magnetic excitation spectrum of UN and UAs exhibits only a broad response, whereas well defined spin‐wave branches have been observed for USb and the cerium monopnictides. A very detailed study of the magnetic excitations has been performed for CeAs, where the spin‐wave dispersion is split into two modes of transverse polarization due to the exchange anisotropy. One of these modes exhibits nearly zero energy gap and quadratic dispersion which has not previously been observed in antiferromangets. A generalized random‐phase‐approximat...
TL;DR: The crystal and magnetic structures of polycrystalline CeDx(2.18 and 2.29 respectively) were studied in this article, where they showed that the magnetic ordering changes from ferromagnetism (Tc=3.7(2)K, ordered magnetic moment mu (Ce3+)=1.1(1) mu B at 1.3K, mu //(111)).
Abstract: The crystal and magnetic structures of polycrystalline CeDx(2.2 or=2.90 remains approximately cubic down to 1.5K, second-order phase transitions to ordered structures with tetragonal symmetry (basic translations at approximately ac, ct approximately 2ac, space group I4; in contrast to Titcomb and co-workers (1974)) occur at temperatures Tc=290(3) and 330(5)K for x=2.18 and 2.29 respectively. Between x=2.29 and x=2.96 the magnetic ordering changes from ferromagnetism (Tc=3.7(2)K, ordered magnetic moment mu (Ce3+)=1.1(1) mu B at 1.3K) to FCC II antiferromagnetism (TN=4.2(2)K, mu (Ce3+)=0.6(1) mu B at 1.3K, mu //(111)).
TL;DR: In this article, the antiferromagnetic structure of MnS 2 has been re-examined by neutron diffraction from a single crystal, and the phase transition has been found to be of the first order without any detectable thermal hysteresis.
TL;DR: In this paper, the authors performed diffraction and magnetization study of polycrystalline NdRh2Si2 and ErRh2S2 in the temperature range from 4.2 to 293 K. Both compounds exhibit antiferromagnetic ordering below TN = 53 K and TN = 12.8 K respectively.
TL;DR: In this paper, a basse temperature par diffraction RX, diffraction de neutrons and calorimetrie differentielle a balayage is derived for helimagnetiques doubles, avec vecteur de propagation selon a et/ou c, dominent dans l'etat magnetique cooperatif.
Abstract: Etude a basse temperature par diffraction RX, diffraction de neutrons et calorimetrie differentielle a balayage. Les arrangements helimagnetiques doubles, avec vecteur de propagation selon a et/ou c, dominent dans l'etat magnetique cooperatif. Les modes H a et H c coexistent pour un etroit domaine de composition autour de t=0,37
TL;DR: In this paper, a study of the magnetic structure of the intermetallic compound DyRh2Si2 (I4/mmm) was performed using neutron (2.459 A) diffraction of a powder sample.
Abstract: A study of the magnetic structure of the intermetallic compound DyRh2Si2 (I4/mmm) was performed using neutron (2.459 A) diffraction of a powder sample. Below 52 K the diffraction patterns reveal a type I antiferromagnetic structure on the Dy sublattice, with a magnetic moment of 9.9±1 μB per ion along c. The appearance of a weak 001 reflection below 18 K is interpreted as due to canting (∼19 °) of the Dy moment from the c axis.
TL;DR: In this article, the results of extensive magnetisation, X-ray and neutron powder diffraction measurements on the intermetallic compound series Ni2-xMnSb, for 0⩽x ⩽1, are reported.