Showing papers on "Magnetic structure published in 1970"
TL;DR: In this article, the properties of perovskite-type oxide LaMnO 3 were studied experimentally and theoretically using a phenomenological approach or the Spin-Hamiltonian formalism.
Abstract: Magnetic properties of the perovskite-type oxide LaMnO 3 were studied in detail, experimentally and theoretically. The properly stoichiometric LaMnO 3 had a weak ferromagnetic moment in addition to the antiferromagnetic character with a Neel temperature of 141°K. It was found to be a parasitic weak ferromagnet. These results can be successfully explained using a phenomenological approach or the Spin-Hamiltonian formalism. The theoretical results show that the antiferromagnetic spin axis should be along the b -axis of the orthorhombic crystal axes and the ferromagnetic moment along the c -axis. The relation between a layer-type ( A -type) antiferromagnetic superexchange interaction and the Jahn-Teller distortion of Mn 3+ ions is also discussed.
217 citations
TL;DR: In this article, a neutron diffraction study has been made on single crystal specimens of α-Mn at 4.4°K, 60°K and several other temperatures.
Abstract: A neutron diffraction study has been made on single crystal specimens of α-Mn at 4.4°K, 60°K, and several other temperatures. Five types of magnetic form factor were in turn employed in the analysis. The magnetic structure is described by a single non-collinear configuration throughout the temperature range below T N with relatively large magnetic moments in Sites I, II and small moments in Sites III, IV, irrespective of which form factor is chosen. The experimental results seem to favor a localized moment model rather than a spin density wave model. When the analysis is based on the localized moment model, moments of 1.9, 1.7, 0.6 and 0.2 5 µ B may be assigned to Site I, II, III, and IV, respectively at 4.4°K, and the spin density in the atom is a superposition of a positive 3d-density and a negative 4s-density. The dependence of the effective exchange interaction coefficient on the inter-atomic distance is discussed.
167 citations
TL;DR: In this paper, the scattering of moderately high-energy x rays from electrons in magnetic solids is analyzed, and it is shown that the incoherent Compton scattering of polarized x rays can be used to determine the spin-dependent momentum distribution function of electrons in ferromagnetic materials.
Abstract: The scattering of moderately high-energy x rays from electrons in magnetic solids is analyzed. We show that (a) the incoherent Compton scattering of polarized x rays can be used to determine the spin-dependent momentum distribution function of electrons in ferromagnetic materials, and (b) the coherent Bragg scattering of unpolarized x rays can be used to determine the magnetic structure of antiferromagnetic solids below their transition temperature.
159 citations
TL;DR: In this article, a new electronic configuration involving localized $6s$ electrons is hypothesized for the Sm ions in Sm${\mathrm{B}}_{6}$, which is successful in explaining earlier results of susceptibility measurements and new Mossbauer spectroscopy data reported here.
Abstract: A new electronic configuration involving localized $6s$ electrons is hypothesized for the Sm ions in Sm${\mathrm{B}}_{6}$. The model is successful in explaining earlier results of susceptibility measurements and new M\"ossbauer spectroscopy data reported here.
134 citations
85 citations
TL;DR: In this article, the Mossbauer effect has been measured on powder samples of the h.p.c. iron nitride ϵ-Fe3.2N at 295 °K.
Abstract: The Mossbauer effect has been measured on powder samples of the h.c.p. iron nitride ϵ-Fe3.2N at 295 °K. The measurements indicate, that there are two kinds of Fe-atoms with different environments in this material. This is in accordance with previous X-ray investigations by which it was found that in ϵ-iron nitrides the N-atoms are highly ordered in such a way that e.g. in ϵ-Fe3.2N the Fe-atoms have either one or two N-atoms within their nearest neighbourhood. Furthermore the average magnetic moment of the Fe-atoms in ϵ-Fe3.2N has been measured to be 1.97 μB. Using this value together with the Mossbauer data the magnetic moments of the Fe-atoms are estimated. The moments obtained are 2.4 μB and 1.9 μB respectively. These values are interpreted by similar considerations by which the magnetic structure of the f.c.c. γ′-iron nitride Fe4N has been explained previously in the literature.
65 citations
TL;DR: In this paper, the spinel form of Fe3S4 has been prepared hydrothermally and two distinct patterns associated with iron on antiparallel sublattices in A and B sites were identified.
62 citations
TL;DR: For the normal spinel ZnFe2O4 one indicates colinear and non-colinear spin arrangements which are equally compatible with neutron diffraction powder intensities, observed at 4.2 K as discussed by the authors.
60 citations
TL;DR: In this article, various barium orthoferrates over wide Fe 4+ concentrations were prepared and their magnetic properties were investigated, and the triclinic I and rhombohedral phases were shown to have a magnetic structure of one-dimensional antiferromagnet.
Abstract: Various barium orthoferrates over wide Fe 4+ concentrations were prepared and their magnetic properties were investigated. The hexagonal phase with large Fe 4+ concentration is ferromagnetic above the anomaly point. With increasing Fe 3+ , it tends to be antiferromagnetic. The cubictetragonal phases are paramagnetic with positive paramagnetic Curie temperature. In these phases, the Fe 4+ -Fe 4 interaction is ferromagnetic, but the Fe 3+ -Fe 4+ and Fe 3+ -Fe 3+ interactions are antiferromagnetic. Some of the Fe 3+ and Fe 4+ ions in these phases take low spin states due to strong uniaxial crystalline fields caused by neighbouring oxygen vacancies. The triclinic I phase seems to have a magnetic structure of one-dimensional antiferromagnet. The magnetic structures of the triclinic II and rhombohedral phases resemble that of the triclinic I.
58 citations
TL;DR: In this paper, it was shown that the powder data cannot indicate an unambiguous magnetic structure, but the magnitude of the ordered moment can be fixed The rms moments associated with ordering of the first and second kinds are 10 and 060 µ� B per nickel atom, respectively, and the total moment is 117 µ� B per Nickel atom.
Abstract: The transition metal dichalcogenides exhibit a wide variety of both electrical and magnetic properties, from insulators to superconductors and from ferromagnetism through antiferromagnetism to diamagnetism NiS
2 is a semiconductor with an anomalous paramagnetic behavior which leaves in doubt the existence of a local moment Previous neutron diffraction data have failed to show any ordering down to 42°K Our neutron powder diffraction data on stoichiometric NiS
2 show a transition at 40°K to a structure which can be described as ordering of the first kind This is followed by an abrupt transition at 30°K in which additional diffraction peaks appear and these are consistent with ordering of the second kind Despite the fact that the powder data cannot indicate an unambiguous magnetic structure, the magnitude of the ordered moment can be fixed The rms moments associated with ordering of the first and second kinds are 10 and 060 µ
B per nickel atom, respectively, and the total moment is 117 µ
B per nickel atom
55 citations
TL;DR: The orthorhombic compounds BaMF4 (Mn, Fe, Co, or Ni) have recently been found to undergo antiferromagnetic transitions at low temperatures as mentioned in this paper.
Abstract: The orthorhombic compounds BaMF4 (M=Mn, Fe, Co, or Ni) have recently been found to undergo antiferromagnetic transitions at low temperatures. Susceptibility measurements on BaNiF4 reveal that a broad maximum occurs at about 150°K similar to that observed in a number of layer‐type structures. As the temperature is lowered, χ∥ along b decreases rapidly, while χ⊥ goes through a shallow minimum around 50°K. At 77°K, no magnetic order can be detected in powder neutron diffraction patterns of BaNiF4, but at 4.2°K there are magnetic peaks which can be indexed on a unit cell doubled along the b and c directions (A21am orientation). The magnetic structure consists of puckered (010) sheets within which the moments are coupled antiparallel to neighboring moments about 4‐A apart. However, the crystal structure is such that the net interaction between adjacent sheets is zero, and ordering in the b direction depends upon interactions between second nearest sheets 14‐A apart. This is very similar to the situation in K2N...
TL;DR: In this paper, the magnetic properties of monocrystalline Pr and Nd single crystals have been studied by neutron-diffraction and susceptibility measurements, and it was shown that the complex magnetic structure of Nd is substantially modified by a magnetic field.
Abstract: The magnetic properties of Pr and Nd single crystals have been studied by neutron-diffraction and susceptibility measurements. In contrast to earlier results on polycrystals, monocrystalline Pr is found not to be magnetically ordered, because of crystal field effects, but a magnetic field induces a large moment. Anisotropic effective exchange results in a large magnetic anisotropy. The complex magnetic structure of Nd is substantially modified by a magnetic field.
TL;DR: In this paper, the magnetic superlattice reflections for both compounds can be indexed on the basis of a hexagonal unit cell with dimensions a = 3 a 0 and c = c 0, where a0 and c0 are the dimensions of the chemical unit cell.
TL;DR: In this paper, the magnetic properties of the rare earth alloys RAl, RNi, and R3Ni were studied in high magnetic fields up to 70 kOe.
Abstract: We have studied the magnetic properties of the rare‐earth alloys RAl, RNi, and R3Ni, with R = Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, in high magnetic fields up to 70 kOe. For the three series, the magnetic properties differ according to the alloyed rare earth. The compounds RAl of DyAl type and RNi of FeB type are ferromagnetic or antiferromagnetic. The compounds R3Ni exhibit metamagnetism, except Tm3Ni which has a ferromagnetic behavior. We have studied the magnetic structure of NdAl, TbAl, HoAl, ErAl, TmAl, NdNi, ErNi, HoNi, and Er3Ni by neutron diffraction. They have all a noncolinear magnetic structure except NdNi, in which the magnetic moments are parallel. We have studied the stability of the magnetic structures by means of group theory; they are all stabilized by strongly anisotropic magnetic interactions between rare‐earth atoms.
TL;DR: In this paper, a non-collinear magnetic structure for α-Mn is proposed, and the magnetic point group is isomorphic with either D 2 d of C 3 v depending on whether the principal axis is along either a or a, respectively.
Abstract: A systematic method of magnetic structure analysis is developed and applied to the case of α-Mn. Scalar, vector, and tensor quantities in a phenomenological thermodynamical potential are expanded in complete sets of basis functions which form irreducible representations of the space group, and on this basis, a possible magnetic structure for α-Mn is discussed. A non-collinear magnetic structure containing thirteen parameters is proposed. The magnetic point group is isomorphic with either D 2 d of C 3 v depending on whether the principal axis is along either a or a , respectively. Possible modes of magnetostrictive atom-displacement are also discussed.
TL;DR: A detailed neutron diffraction study of Pd 2 MnSn and Cu 2 MnIn shows that both have the fully ordered L2 1 type of Heusler alloy structure and are ferromagnetic with 190 and 575°K as their respective Curie temperatures as mentioned in this paper.
Abstract: A detailed neutron diffraction study of Pd 2 MnSn and Cu 2 MnIn shows that both have the fully ordered L2 1 type of Heusler alloy structure and are ferromagnetic with 190 and 575°K as their respective Curie temperatures. Pd 2 MnGe shows a preferentially disordered L2 1 structure with 0.98 Pd + 0.02 Mn on the A- and C-sites and 0.96 Mn + 0.04 Pd on the B-sites. The B-site Mn moments are aligned antiparallel to those on the A- and C-sites and its Curie temperature is 260°K. The alloy CoMnSb has been found to have an incompletely filled L2 1 structure and is ferromagnetic below 430°K.
TL;DR: In this paper, a neutron diffraction study of three single-crystal Tb-Ho alloys was performed, containing 10, 50, and 90% Ho, and they were studied in detail from 5-298°K.
Abstract: A neutron diffraction study of single‐crystal Tb–Ho alloys is reported. Three single‐crystal samples, containing 10%, 50%, and 90% Ho, were studied in detail from 5–298°K. We find that all three alloys have similar ordered phases with uniform magnetic structures. Between the Neel temperature and Curie temperature, each alloy exhibits a spiral magnetic structure with the magnetic moments confined to the basal plane of the hcp structure. The temperature dependence of the interplanar turn angle changes gradually from that similar to pure Tb to that of pure Ho as the Ho concentration increases. Below the Curie temperature, all the alloys exhibit a collinearly ferromagnetic structure with the magnetic moments parallel to or closely parallel to the basal plane. The transition temperatures agree well with the corresponding values determined from magnetization measurements. The observed magnetic form factors also show a gradual change in shape as the Ho concentration increases from the shape similar to pure Tb to...
TL;DR: The chemical and magnetic structure of MnAs0.92P0.08 has been studied from 10° to 427°K using x-ray and neutron diffraction.
Abstract: The chemical and magnetic structure of MnAs0.92P0.08 has been studied from 10° to 427°K using x‐ray and neutron diffraction. Below 440°K MnAs0.92P0.08 is orthorhombic (Pnma; c>a>b), and a refinement of the x‐ray data at lower temperatures showed that there was a continuous change of the Mn and As(P) atomic coordinates. The nuclear scattering, calculated using the x‐ray parameters, was subtracted from the measured neutron intensities. The resultant magnetic scattering indicated there must be both ferromagnetic and antiferromagnetic spin components. The orthorhombic magnetic space group, Pn′m′a, is consistent with both types of spin components and the observation of the 001 antiferromagnetic peak. A least‐squares fit at 200°K gave a ferromagnetic component of 2.0 μB along the c axis and an antiferromagnetic component of 1.6 μB along the a axis. Below 150°K further weak magnetic lines appear, indicating the onset of long period modulations. The Mn moment is consistent with a high spin rather than a low spin,...
TL;DR: The magnetic structure of vivianite, Fe3(PO4)2, has been determined from a single crystal neutron study as mentioned in this paper, and the structure is antiferromagnetic but not collinear; an angle of 42 degrees exists between the spin directions on the FeI and FeII sublattices.
Abstract: The magnetic structure of vivianite, Fe3(PO4)2.8H2O has been determined from a single crystal neutron study. The structure is antiferromagnetic but not collinear; an angle of 42 degrees exists between the spin directions on the FeI and FeII sublattices. The noncollinear aspects of the proposed structure have been confirmed by Mossbauer measurements with the specimen in an external magnetic field. The temperature dependence of the neutron magnetic reflections indicate a Neel temperature of 8.84+or-0.05 K; no evidence is found for any long range magnetic order above this temperature. The values of the effective fields at the iron nuclei at 1.3 K are 175 kG(FeI) and 275 kG (FeII).
TL;DR: In this article, the magnetic properties of CoCl2·6H2O have been studied at temperatures above and below the Neel temperature, and the spin direction is along the c axis.
Abstract: Neutron diffraction data on the (h0l) zone of CoCl2·6H2O have been taken at temperatures above and below the Neel temperature. Measurements at 77°K confirm that the hydrogen parameters are essentially the same as for NiCl2·6H2O. Below the measured Neel temperature of 2.25°K, the magnetic structure consists of antiferromagnetic (001) planes with an antiferromagnetic coupling between planes, and has the magnetic space group Cc2 / c. Magnetic intensities taken at 1.5°K indicate that the spin direction is along the c axis. This is in agreement with reported susceptibility data.
TL;DR: A neutron diffraction investigation of the magnetic structure of gamma-manganese alloys is described in this paper, where the alloys are confirmed to have a simple antiferromagnetic structure.
Abstract: A neutron diffraction investigation of the magnetic structure of gamma -manganese alloys is described The alloys are confirmed to have a simple (type 1) antiferromagnetic structure In addition, the behaviour of a broad intense peak in the neutron diffraction pattern is examined This peak, which occurs near the position of the absent (100) Bragg reflection, has in the past been identified with magnetic inelastic and magnetic short-range order scattering The effects of alloy composition and temperature on the peak are investigated, and its detailed shape is examined using special 'null-matrix' alloy samples It is concluded that atomic short-range order accounts for the peak in the majority of cases
TL;DR: In this article, it was shown that MnB 2 is an antiferromagnet with a magnetic moment of about 3 µ B per Mn atom and a Neel point of 760°K.
Abstract: Measurements of the Mn 55 nuclear magnetic resonance, high-field susceptibility, magnetic anisotropy and electrical resistivity have been performed on intermetallic compound MnB 2 . It is proposed that MnB 2 is an antiferromagnet with a magnetic moment of about 3 µ B per Mn atom and a Neel point of 760°K. The weak ferromagnetism below 157°K is attributed to the tilting of the antiferromagnetic moments out of the c -plane. Unusual temperature dependence of the susceptibility and the mechanism for the tilting are discussed on the basis of the s - d exchange interaction.
TL;DR: In this paper, a detailed analysis of the magnetic structure of the compound with x = 1.9 is performed and the magnetic unit cell is 2 a, 2a, 2 a and the spin arrangement as for MgCr2O4.
Abstract: ZnFe2-xCrxO4 spinels with x = 0, 0.1, 0.5, 1.0, 1.5, 1.9, and 2.0 were investigated. The lattice and the oxygen parameter were determined by means of X-ray and of neutron diffraction methods, The neutron diffraction pattern at T = 4.2 °K for a compound with x = 0.1 is similar to those of ZnFe2O4. For 0.5 ≦ x ≤ 1.5 short-range magnetic order is observed at low temperatures. A detailed analysis of the magnetic structure of the compound with x = 1.9 is performed. The magnetic unit cell is 2 a, 2 a, 2 a and the spin arrangement as for MgCr2O4. The Neel temperature is TN = 16 °K and the magnetic moment of the Cr3+ ion is equal to 2.4 μB.
[Russian Text Ignored]
TL;DR: In this article, the authors performed magnetic susceptibility measurements on the MnPd3 phase in both completely ordered and partially disordered states and found that the magnetic moments to the tetragonal axis became atomic order-dependent at 25%, increasing from 0° towards 90° with decreasing order.
Abstract: Neutron diffraction and magnetic susceptibility measurements were performed on the MnPd3 phase in both completely ordered and partially disordered states. The antiferromagnetic configuration of MnPd3 was confirmed in the range of 23–30 at.% Mn. The angle φc of the magnetic moments to the tetragonal axis, which is 0° below 25% and 90° at higher Mn concentrations, was observed to become atomic order‐dependent at 25%, increasing from 0° towards 90° with decreasing order. A decrease in the Neel temperature with decreasing order was also observed. The 90° turn in the direction of the magnetic moments is thought to be due to the effect of the nearest‐neighbor Mn pairs which are formed either because of the partial disorder of the stoichiometric alloy or owing to the excess Mn atoms in the ordered nonstoichiometric alloys.