Types Of Magnetic Structures Research Articles

Local magnetic structure and anomalies of magnetic hyperfine interactions of57Fe and119Sn nuclei in lithium aluminium ferrites

The57Fe and119Sn Mossbauer spectra of ordered ferrites Li0.5Fe2.5−xAlxO4∶Sn for 0.8<x<1.0 (the compensation point region) have been studied. The spin glass type magnetic structure with the spin canting angle depending on temperature and aluminium concentration is established. Anomalies in the temperature dependence of the hyperfine magnetic field at tin nuclei have been found near the compensation point of the ferrites

Band Structures and Physical Properties of Magnetic Layered Semiconductors MPS3

The band structures of manganese chalcogeno-phosphate MnPS 3 and iron chalcogeno-phosphate FePS 3 are calculated self-consistently. From the calculation of the total energies of two types of magnetic structures of MnPS 3 , the experimentally observed magnetic structure is proved more stable. Furthermore, by comparing the band structures of MPS 3 family (M=Mn, Fe, Ni, Zn), it is found that FePS 3 and NiPS 3 are more active to the Li intercalation than ZnPS 3 and MnPS 3 , and that NIPS 3 is the best cathode material in secondary lithium batteries in the MPS 3 family.

セレン化物および酸化物の人工格子単結晶の生成と構造

Structures of artificial superlattices of a PbSe-SnSe couple grown on the NaCl (100) by evaporation were investigated by the X-ray diffraction and the cross-sectional transmission electron microscopy. PbSe and SnSe have different crystal structures and a large lattice mismatch. The superlattices, (PbSe)m(SnSe)n adopt four types of lattice structures depending on m and n.The single crystal films of (CoO)m(NiO)n superlattices were grown on the single crystal α-Al2O3 (0001) by reactive evaporation. The superlattices with the good crystalline quality revealed well-defined satellite X-ray peaks due to an artificial period. A magnetic Bragg peak indexed as (1/2 1/2 1/2) in neutron dif-fraction pattern was observed for superlattices with each layer less than 2 nm (m, n≤8) and a magnetic structure type FCC2 with spin axis lying in the (111) plane grown was suggested. The Néel temperature was found to vary as a linear function of n/(m+n).

Modulated spin structures due to the four-spin exchange interaction in some intermetallic compounds

The model consisting of the two-spin exchange interaction and the four-spin one is studied. The systematic change of the magnetic structures among MnS2, MnSe2 and MnTe2 is shown to be well-explained by this model. The three types of magnetic structures of EuSe is also discussed.

The low temperature magnetic anisotropy of the RRh2Si2 system (R: Rare earth elements)

The magnetic anisotropy of RRh2Si2 which has an AFI type magnetic structure can be explained well using a single R3+ ion Hamiltonian which includes the crystal field term and the isotropic exchange term under the two dimensional molecular field approximation, when appropriate crystal field parameters are adopted.

Itinerant antiferromagnetism of the Ti-Si solid solutions

Magnetic susceptibility measurements of Ti-Si solid solutions are reported. Silicon by alloying acts on the Néel temperature of pure titanium. The Néel temperature decreases monotonously with increasing silicon concentration. The experimental and theoretical magnetic phase diagrams are in good agreement. This means that the antiferromagnetism of the Ti-Si solid solutions can be interpreted in terms of itinerant electron antiferromagnetism of the SDS type magnetic structure.

Nonlinear modification of the hybridization interaction due to band polarization in the magnetically ordered state inf1systems

The hybridization between the f level and the band electrons changes the properties of the band states. In a magnetically ordered system, where the ordering results from the hybridization-mediated two-ion interaction, as in the cerium monopnictides, the band density of states at the Fermi level can be changed. This, in turn, can change the two-ion interaction which is mediated by the band, as in the Ruderman-Kittel-Kasuya-Yosida interaction. Such a change depends on the type of magnetic structure. Under certain conditions, this effect can increase the anisotropy favoring moment alignment along the cube-edge direction.

Spectroscopic Study of the Crystal Field Splittings in TbPO4

AbstractThe optical absorption and emission spectra of Tb3+ in TbPO4 in its tetragonal structure above 2.3 K are studied to obtain the energies, symmetry types, and wave functions of mainly the lowest crystal field components of the ground term 7F6. Crystal field parameters are evaluated and used to calculate the anisotropy of the single‐ion energy in a semi‐classical way. This gives interesting indications for the types of magnetic structures and Jahn‐Teller distortion which occur in this substance below 2.3 K.

Magnetic structures of the rare earth orthotitanites RTiO 3; R = Tb, Dy, Tm and Yb

The magnetic structures of the rare earth orthotitanites, RTiO 3, R = Tb, Dy, Tm and Yb, have been solved using neutron powder diffraction techniques. Two different types of magnetic structure have been found. One has the titanium and rare earth moments antiparallel along the c axis. The other structure has the rare earth moments in the ab plane with both ferromagnetic and antiferromagnetic components. In TbTiO 3, the terbium moment of (8.1 ± 0.4)μ β has ferromagnetic and antiferromagnetic components along the [100] and [010] directions, respectively, with the moments lying at an angle of (36 ± 3)° to the [100] direction. In DyTiO 3, the dysprosium moment of (9.7 ± 0.7)μ β has ferromagnetic and antiferromagnetic components along the [010] and [100] directions, respectively, with the moments making an angle of (31 ± 5)° to the [010] direction. TmTiO 3 has a thulium moment of (6.0 ± 0.4)μ β in a ferromagnetic array along the [001] direction. The average titanium moment in the orthotitanites is (0.7 ± 0.3)μ β in a direction antiparallel to the ferromagnetic component of the rare earth moment. The ytterbium moment in YbTiO 3 is quenched. It is found to be (1.7 ± 0.2)μ β assuming a moment direction along [001]. The rare earth moment directions are found to be remarkably consistent in the series RMO 3, M = Ti, Cr, Fe and Al.

Heat capacity and phase transition of a five-coordinated antiferromagnet, IODOBIS ( N,N-diethyldithiocarbamato) iron (III), in the temperature range from 0.4 TO 300 K

The heat capacity of iodobis ( N, N-diethyldithiocarbamato) iron (III) has been measured between 0.4 and 300 K. A phase transition from an antiferromagnetic to a paramagnetic state was found at T N = (1.937 ± 0.010) K, and a Schottky-type anomaly arising from a zero-field single ion splitting was observed around 12 K. The total magnetic entropy and enthalpy, including the phase transition and the Schottky-type anomaly, are 11.36 JK −1 mol −1 and 134.5 J mol −1, respectively. The entropy is approximately equal to R ln 4 ( = 11.53 JK −1 mol −1), confirming that the spin manifold is really a quartet. The entropy and enthalpy due to the phase transition are estimated to be (5.57±0.01) JK −1 mol −1 and (13.2±0.05) Jmol −1, respectively. The entropy and enthalpy above t n are quite large, as in the case of the related compound chlorobis ( N, N-diethyldithiocarbamato) iron (III). This fact suggests that the present complex may be considered to have a two-dimensional type of magnetic structure from a thermodynamic point of view. A correlation diagram between the transition entropy and energy is proposed, this being a diagnostic for the determination of the magnetic dimensionality.

Study of metals by means of positive muons

This review discusses a number of questions related to the use of the muon method for the study of metals. The possibilities of the method for the study of normal metals, superconductors, and ferromagnetic materials are analyzed. A systematic comparison of theory and experiment is made. It is shown that the method permits determination of the local magnetic fields at crystallographic sites, the type of magnetic structure in complicated ferromagnetic crystals (rare earth metals), analysis of the magnetic texture (grain orientation) of electrical steels, diagnosis of the interstitial sites occupied by a proton or muon, determination of the diffusion rate and the degree of distortion of the crystal lattice, and study of phase transitions in rare earth metals and spin glasses. In normal metals the muon method permits determination both of the muon diffusion rate and of the nature of diffusion (classical or quantum), the Knight shift in the muon, the charge state of a proton or muon in the metal, and the distortion of the crystal lattice. For superconductors the method permits information to be obtained which is inaccessible by other means, particularly determination of the ratio of the normal and superconducting phases and study of the dynamics of destruction and appearance of the superconducting state. The prospects for development of the muon method for study of the properties of metals are demonstrated.

Weak field magnetic transition in Tb 3Fe 5O 12

A jump like magnetic transition is observed at relatively weak field in Tb 3Fe 5O 12 when the magnetic field is applied along the hard axis and no transition is observed with the field applied along the easy axis. We believe that this evolution is related to the ”Umbrella” type magnetic structure known to exist in Tb 3Fe 5O 12 at low temperatures.

The magnetic structure of the rare earth tetraborides ErB4 and DyB4

Neutron diffraction studies were performed on the compounds ErB4 and DyB4 at 4.2 and 300 K. Both compounds are antiferromagnetically ordered at 4.2 K. A determination of the magnetic structure type is given for ErB4 and DyB4. The magnetic intensities were studied as a function of temperature, leading to Néel temperatures TN=16.3 K (ErB4) and TN=21 K (DyB4). The relative stability of several simple magnetic structures, appropriate to RB4, are discussed in terms of the RKKY model, together with previously reported results of magnetization and NMR studies on these compounds.

Study by Mössbauer spectroscopy of arsenides Fe 2− xMn xAs

The study by Mössbauer spectroscopy of the Fe 2− x Mn x As series confirms that the iron atom completely occupies site I of the structure and leads to Néel temperatures in aggeement with those deduced from magnetic susceptibility measurements. In the range x = 0.8 to x = 1.4, the hyperfine structure is unresolved. On passing from Fe 2As to Mn 2As, three types of magnetic structures are encountered; contrary to the conclusion drawn from neutron diffraction measurements, the spins in Mn 2As are not perpendicular to the c-axis, and FeMnAs does not have the magnetic structure of Mn 2As. The internal magnetic field curves as a function of temperature are in this series either over-Brillouin with first-order antiferromagnetic (AF) to paramagnetic (P) transition or under-Brillouin. In order to explain the set of the observed magnetic anomalies, the existence of itinerant magnetism is postulated.

Magnetic properties of some light rare−earth compounds with CsCl structure

Neutron−diffraction studies were performed on the compounds PrZn, NdZn, NdMg, and NdAg. The lattice constants were determined at 300 and 4.2 K. For all compounds the CsCl structure was confirmed at room temperature. The compound PrZn was found to be subject to a tetragonal distortion at 4.2 K. A very small tetragonal distortion exists probably also in NdZn and NdMg at 4.2 K. the magnetic moment of the rare−earth component and the magnetic structure type was determined. All compounds are antiferromagnetic at 4.2 K, PrZn and NdMg with the 〈0,0,π〉 structure, NdAg with the 〈π,π,0〉 structure. In view of the generally accepted explanation of the magnetic properties of CsCl−type intermetallics in terms of the RKKY model these findings for PrZn and NdMg are remarkable and form a discrepancy with the ferromagnetic nature of the heavy rare−earth counterparts of these compounds.

Magnetic Properties of(V1−xCrx)2O3

The magnetic susceptibility of the ${({\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x})}_{2}{\mathrm{O}}_{3}$ system ($0\ensuremath{\le}x\ensuremath{\le}1$) has been studied over the temperature range 4.2-1000 \ifmmode^\circ\else\textdegree\fi{}K. For $0\ensuremath{\le}x&lt;0.035$, the susceptibility data clearly indicate both the high-temperature transition from a paramagnetic insulating to a paramagnetic metallic state with decreasing temperature and the sharp low-temperature transition from the paramagnetic metallic phase to the insulating antiferromagnetic phase. Separation of the total susceptibility into a temperature-independent Van Vleck term and a temperature-dependent term ${\ensuremath{\chi}}_{d}$ yields Curie-Weiss behavior for ${\ensuremath{\chi}}_{d}$. As $x$ increases from 0 to 0.035, the extrapolated paramagnetic Curie temperature of the insulating high-temperature phase decreases from 600 to 350 \ifmmode^\circ\else\textdegree\fi{}K and the effective moments from $2.96{\ensuremath{\mu}}_{B}$ to $2.30{\ensuremath{\mu}}_{B}$ per magnetic ion. The change from the ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$-type magnetic structure to the ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ type occurs in the region $0.21\ensuremath{\le}x\ensuremath{\le}0.45$. The magnetic susceptibility data are consistent with the picture developed for pure and Cr-doped ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ on the basis of resistivity and x-ray investigations at atmospheric and elevated pressures.

Magnetic Structure of MnSO4

The magnetic structure of MnS${\mathrm{O}}_{4}$ has been determined from a powder neutron-diffraction study. It consists of a cycloidal spiral arrangement related to the simple CrV${\mathrm{O}}_{4}$ type of magnetic structure, in which ferromagnetic (001) sheets are coupled antiparallel to adjacent sheets. The propagation vector of the spiral is directed along the $a$ axis, with a periodicity of 30 \AA{} (about $6a$), and the spiral spin components lie in the $\mathrm{ab}$ plane. The moment of each ${\mathrm{Mn}}^{2+}$ ion is $4.8{\ensuremath{\mu}}_{B}$, and the cone half-angle is about 78\ifmmode^\circ\else\textdegree\fi{}.

Magnetic Structure versus Electron Number for Some Rare-Earth Intermetallic Compounds

Neutron diffraction measurements were made on a series of rare-earth compounds in the Tb(Pd, Ag) and Tb(Ag, In) systems. Most of these compounds exhibit the CsCl type of crystal structure and, for these, magnetic structure determinations were made in order to relate the type of magnetic structure to the number of valence electrons. Two types of antiferromagnetic structures were observed; the (ππ0) type consisting of an antiparallel array of ferromagnetic (110) planes of moments, and the (00π) type with ferromagnetic (001) planes of moments alternating in direction. On the basis of 0, 1, 3, and 3 valence electrons for Pd, Ag, In, and Tb, respectively, the (ππ0) structure is found in the region of 3.5 to 4 valence electrons per unit cell and the (00π) structure in the region of 5 valence electrons per unit cell.

A magnetic and neutron diffraction study of the Cr 2O 3-Fe 2O 3 system

The magnetic structures of solid solutions (1− x)Cr 2O 3- xFe 2O 3 have been determined by neutron diffraction and magnetic measurements. The different antiferromagnetic structures of Cr 2O 3 and Fe 2O 3 are revealed to be connected through cone spiral structures in such a way that continuity is preserved. For the purpose of describing the latter, the fundamental Cr 2O 3 type of magnetic structure is divided into two sublattices, within each of which the spins are coupled ferromagnetically, with antiferromagnetic coupling between the sublattices. The addition of Fe 2O 3 creates a cone spiral within each sublattice, both the cone axis and the spiral wave vector lying along the hexagonal c-axis. The cone angle increases with increasing Fe 2O 3 content up to x = 0.15. p ]In the region 0.2 ⩽ x ⩽ 0.35, the cone axis lies perpendicular to the c-axis, although the spiral wave vector remains parallel to the latter, resulting in a cycloidal arrangement. The spin components along the cone axis now have the fundamental Fe 2O 3 type of magnetic structure. As the Fe 2O 3 content increases, the cone angle decreases, until finally when this becomes zero, the Fe 2O 3 type of magnetic structure is attained.