bluuebunny/crossref_metadata_2025 huggingface dataset:
THE MAGNETISM OF METALLIC MANGANESE ALLOYS
Authors: HOLDEN T.M. , MIKKE K. , FAWCETT E. , FERNANDEZ-BACA J.A.
Published: November 2004

The magnetic excitations in antiferromagnetic manganese-copper and manganeseiron alloys are characterized by high spin-wave velocities, an energy gap at long wavelengths and wavelength dependent damping. There are strong elastic constant anomalies above TN as well as magnetoelastic distortions below TN. The theoretical explanation of these effects is reviewed.
HIGH ENERGY MAGNETIC EXCITATIONS IN SINGLE DOMAIN HOMOGENEOUS ANTIFERROMAGNETIC γ-Mn(18%Cu) ALLOY AT 10 K
Authors: MIKKE K. , HOLDEN T.M. , FERNANDEZ-BACA J.A. , FAWCETT E. , JANKOWSKA-KISIELIŃSKA J.
Published: November 2004

Measurements of spin waves in homogeneous antiferromagnetic single domain fct γ-Mn(18%Cu) alloy at 10 K were performed up to energies of 82.7 meV yielding v=224±3 meV Å, Eg=7.8±0.2 meV and damping parameters Γ0=2 meV and Γ1=101.4±2.4 meV Å. There is a evidence on the anisotropy of the spin wave dispersion relation.
A CALCULATING METHOD OF MAGNETIC ENERGY FOR A CONSTRAINED MAGNETIZED STATE OF ITINERANT ELECTRONS
Authors: TAKAHASHI ICHIROU
Published: November 2004

A method to calculate the magnetic energy is derived for a constrained magnetized state of itinerant electrons. The method can be used to describe non-collinear magnetism of itinerant electrons. The magnetic energy for a constrained magnetized state is obtained by using functions that are derivatives of the total energy with respect to the magnetic moments. In the local spin density approximation at zero temperature, standard methods of band structure calculation can be used for the numerical calculation in the method. Non-collinear magnetism of FexNi1−x Invar alloy at zero temperature is investigated by using a simple model of alloys and LMTO method for first application of the method. Several stationary magnetized states are found for Fe0.7Ni0.3 alloy by the numerical calculation, in which there are non-collinear magnetized states.
MICROSCOPIC THEORY OF MARTENSITIC TRANSFORMATION IN Fe1−xNix
Authors: HOFFMANN E. , HERPER H. , ENTEL P. , MOHN P. , SCHWARZ K.
Published: November 2004

Fixed-spin-moment band-structure calculations of ordered fcc Fe3Ni reveal Fermisurface nesting, which can give rise to a Kohn-like anomaly. This nesting behaviour is very similar to what has recently been seen in nonmagnetic NixAl1–x.1 Using the method of Varma and Weber2 we discuss the renormalized phonon spectrum of Fe3Ni and investigate how the phonon softening and the martensitic transformation depend on the Fermi-surface nesting.
MAGNETOVOLUME EFFECTS IN Fe3Pt
Authors: MATAR S. , TEICHMANN J. , MOHN P.
Published: November 2004

Equilibrium values of the energy for the magnetic and non-magnetic structures were derived for Fe3Pt using the scalar relativistic ASW method. The stable ground state is found to be ferromagnetic. Calculations were extended to obtain total energy curves as a function of moment and volume via the FSM method. Results were fitted using a polynomial in M and V within a Landau-Ginzburg model of spin fluctuations. Relevant properties to Invar such as the magnetic contribution to the thermal expansion coefficient and the critical pressure for the disappearance of magnetism and its pressure dependence were derived.
THE MAGNETOVOLUME EFFECT IN CeAl2
Authors: PANFILOV A.S. , SVECHKAREV I.V. , FAWCETT E.
Published: November 2004

The magnetic susceptibility of CeAl2 was measured under pressure up to 2 kbar at 78, 185 and 296 K. The results are treated in terms of a theory which includes the Kondo effect and crystal field splitting. The derivatives with respect to volume are obtained for the splitting ∆ and the effective sd-f exchange parameter I.
MICROSTRUCTURE AND MAGNETIC PROPERTIES OF Sm2Fe17NNx−ALLOY- POWDERS AND OF BONDED ANISOTROPIC MAGNETS
Authors: WALL B. , KATTER M. , RODEWALD W. , VELICESCU M.
Published: November 2004

In cast Sm2Fe17 ingots minor fractions of SmFe2 and SmFe3 may occur. Nitrogenation of such alloy-powders inidicates that only Sm2Fe17 forms an interstitial solid solution whereas SmFe2 and SmFe3 decompose directly into SmN and α-Fe.

From Sm2Fe17Nx alloy powders with an average particle size of about 3 μm anisotropic magnets were prepared by adding 15 wt% Zn-powder. Annealing at 390 ºC results in intrinsic coercivities > 15 kOe promoted by the formation of an unknown binary Fe8Zn92-compound. Whereas annealing at temperatures > 420 ºC leads to the formation of binary Fe3Zn7 and ternary Sm2FeZn2. By the formation of Sm2FeZn2 from Sm2Fe17Nx+Zn some α-Fe occurs inducing a step in the demagnetization curve J(H).
FIRST-PRINCIPLES CALCULATION OF THE MAGNETOCRYSTALLINE ANISOTROPY ENERGY FOR THE PSEUDOBINARY COMPOUND Y(Co1−xFex)5
Authors: TRYGG JOAKIM , NORDSTRÖM LARS , JOHANSSON BÖRJE
Published: November 2004

From the experimental behavior of the magnetocrystalline anisotropy energies of the pseudobinary compounds Y(Co1−xFex)5, it has been argued that the magnetocrystalline anisotropy energies for YCo5 and the hypothetical compound YFe5 will have different signs. This anomalous behavior is attributed to the change of the number of 3d electrons and their orbital moments when proceeding from YFe5 to YCo5. The magnetocrystalline anisotropy energies are calculated using the linear muffin-tin orbital (LMTO) method in the atomic sphere approximation (ASA) including spin-orbit interaction and orbital polarization. The force-theorem is used to express the total energy difference (between the two directions of magnetization) as a difference in the sum of the single particle eigenvalues. We find that it is possible to predict the correct easy-axis for YCo5 and YFe5. Secondly it is found that the inclusion of orbital polarization is essential for the cobalt compound but less important for the iron compound. The different contributions from the two inequivalent transition metal sites to the anisotropy energy and orbital magnetization are discussed.
EFFECTS DUE TO THE NEAR MAGNETIC TRANSITIONS IN ZrV2
Authors: LERCH P. , MORONI E.G. , JARLBORG T.
Published: November 2004

Local spin density calculations for the large enhanced paramagnet ZrV2 in the C15 structure have been performed. The ground-state is paramagnetic but almost degenerate with the ferromagnetic state. Here we study different ways to trigger ferromagnetism. First we study the possibility of having thermal excitations between non-magnetic and magnetic states, in which case a anti invar effect would be possible. Secondly, in calculations with V core holes which are models of X-ray absorption spectroscopy (XAS) we study the possibility of having induced magnetism via core polarization. Calculations of complete XAS spectra including matrix elements suggest that these nearly magnetic systems are good candidates for giving quite unusual results in spectroscopy measurements.
MAGNETIC PROPERTIES OF THE 3d SUBLATTICE IN RnTm INTERMETALLICS
Authors: RADWAŃSKI R.J. , FRANSE J.J.M.
Published: November 2004

The variation of the 3d magnetic moment and the magnetocrystalline anisotropy (MCA) of the 3d sublattice in 3d compounds with Gd and Y like Y2Fe17, YFe3, YFe2, Y2Fe14B, Y2Co17, YCo5, Y2Co7, YCo3, YCo2 and Y2Co14B is discussed. Dependences of the 3d moment in the Y-T and Gd-T compounds show the induced Co moment in the latter compouds. The concentration dependence of the susceptibility in the Y-Fe, Y-Co and Y-Ni compounds exhibits two particularities marking the magnetovolume effects and the onset of the magnetic ordering. The opposite sign of the MCA of the 3d sublattice in most of the Y-Fe and the Y-Co counterparts provides the strong evidence for the presence of the orbital 3d moment.
3d—MAGNETISM OF THE RT4B COMPOUNDS
Authors: DUNG T.T. , THUY N.P. , HIEN T.D. , HONG N.M. , KHAN D.C. , FRANSE J.J.M.
Published: November 2004

Spontaneous-magnetostriction and FMR studies are reported for the series Y(CO1−xFex)4B with x=0.00, 0.0125, 0.02 and 0.125. For the samples with composition x=0.00, 0.0125 and 0.02, step-like changes of the lattice constants a and c around the spin reorientation temperature TSR are observed. The relative values of the changes in ∆a/a and ∆c/c are of the order of 10−4 but are of opposite signs. The changes in the unit cell volume ∆V/V around TSR are negligible. In the temperature dependence of the average g-values of these samples, a step-like change with a relative value for ∆g/g of 10−2 has been deduced from FMR studies. These results point to a close correlation between the lattice constants and the magnetocrystalline anisotropy of the 3d-lattice and consequently to the role of the orbital moments in the anisotropic properties of the 3d-magnetism in the considered compounds.
MAGNETISATION AND MAGNETORESISTANCE OF Ho2Co17
Authors: KAYZEL F.E. , RADWAŃSKI R.J. , TAI L.T. , BAKKER K. , FRANSE J.J.M.
Published: November 2004

High field magnetisation measurements up to 38 T have been performed on a newly grown single-crystalline Ho2Co17 sample along the main crystallographic directions of the hexagonal cell. The magnetization curve along the easy direction (b-axis) exhibits a metamagnetic-like transition at 23.6 T whereas for the a-axis a similar transition occurs at 31.4 T. The transitions are extremely sharp - much sharper than in previously grown crystals. The transitions are understood as a moment-flip transition associated with the formation of a non-collinear magnetic structure in this ferrimagnetic compound. From the transition-field value the 3d-4f spin-exchange parameter has been derived. Both of these transitions are seen in the magnetoresistance as an abrupt decrease of the resistance.
METAL-INSULATOR TRANSITION IN Yb1–x Gdx Te
Authors: RAVOT D. , GOROCHOV O. , MAUGER A.
Published: November 2004

The metal-insulator transition of Yb1−xGdxTe has been studied by tuning x, since Gd3+ions act as donors. Transport and magnetic properties have been measured for 0<x<1 and T≥4.2K. For x>0.5, the material is a metallic antiferromagnet with a Néel temperature decreasing with x. An outstanding T–1 behavior of the resistivity is observed in a broad temperature range, which we attribute to electron-electron scattering in 3D dimension disordered systems. This behavior is observed in the metallic side, for x in the range 0.2<x≤0.5, and it can be regarded as a pretransition effect to the weak localization regime. This feature gives evidence that localization occurs because random fluctuations are enhanced by the magnetic interaction of the conduction electrons with Gd3+ ions favoring the formation of magnetic polarons. Only for x=0.2 can we observe an activated regime of the resistivity curve with a small activation energy ( ≈ 60K) typical of a thermal activation of the carriers above a mobility edge.
A STUDY OF THE FIELD AND TEMPERATURE DEPENDENT A.C. SUSCEPTIBILITY OF UFe2
Authors: KUNKEL H.P. , SCHACHTER J.M. , WILLIAMS GWYN
Published: November 2004

Measurements of the a.c. susceptibility of UFe2 in the vicinity of the transition to the ferromagnetic state (Tc = 171 K) in various applied fields are presented. Analysis of data acquired in fields above 0.2 kOe suggests a second order phase transition with exponent values that appear consistent with Heisenberg model predictions.
MAGNETIC PROPERTIES OF Nb(Fe1–xA1x)2
Authors: YAMADA Y. , SAKATA A. , MURAKAMI T.
Published: November 2004

The C-14 Laves phase NbFe2 is a very weak antiferromagnet with ferromagnetic spin fluctuations. Magnetic properties were investigated in the Al-substituted system Nb(Fe1–xA1x)2 with x≦0.5 from NMR and magnetisation measurements. It was found that the antiferromagnetism is enhanced by the substitution for x≧0.05, while for x< 0.05 it is suppressed and very weak ferromagnetism appears.
MAGNETIC PHASE DIAGRAM OF PSEUDO-BINARY COMPOUNDS (Mn1–xFex)3Ga WITH THE D019 TYPE STRUCTURE
Authors: HORI T. , NIIDA H. , YAMAGUCHI Y. , NAKAGAWA Y.
Published: November 2004

We have made X-ray diffraction and magnetization measurements for pseudo-binary compounds (Mn1–xFex)3–δ Ga having the DO19 type hexagonal structure. For x≦0.1 the hexagonal structure is slightly distorted to an orthorhombic structure at low temperatures. The Néel temperature of the triangular spin structure decreases monotonically with increasing x, while the compounds with x>0.5 show the typical ferromagnetism. The magnetic phase diagram of the system is proposed.
TRANSITITON FROM A MAGNETIC TO A NONMAGNETIC STATE AS A FUNCTION OF PRESSURE IN MnSi
Authors: PFLEIDERER C. , FRIEND R.H. , LONZARICH G.G. , BERNHOEFT N.R. , FLOUQUET J.
Published: November 2004

We report a study of the temperature dependence of the resistivity ρ(T) of MnSi over the range 20mK to room temperature at hydrostatic pressures of up to 20 kbar. The low temperature form of ρ(T) near the critical pressure Pc=15.5 kbar where the Curie temperature appears to vanish is interpreted in terms of a model of a Marginal Fermi Liquid.
POSSIBLE TWO ELECTRONIC STATES OF Mn ATOMS IN BCC Cr-Mn ALLOYS
Authors: SHIGA M. , WADA H.
Published: November 2004

The thermal expansion, the electrical resistivity and the specific heat of Mn-rich bcc Cr-Mn alloys have been measured. Distinct negative temperature dependence was observed in the thermal expansion and the resistivity at low temperatures. These anomalies are successfully explained on the basis of the two electronic state model by taking account of a local environment effect. An enhanced specific heat at low temperatures is consistently understood in terms of the proposed model.
EVIDENCE FOR KONDO EFFECT OF Pr IN Pd
Authors: RAMAKRISHNAN S. , NIGAM A.K. , SRINIVAS V. , CHANDRA GIRISH
Published: November 2004

We have carried out the resistivity measurements of dilute Pr(0.5, 1.0 and 1.4 atomic percent) in Pd from 60 mK to 300K. The resistivity data of all the alloys show In T behaviour from 21 K to 2 K and Kondo-like saturation in the impurity resistivity from 2 K to 60 mK. These measurements indicate Kondo instability of dilute Pr in Pd. The magnetoresistance data from 4 K to 25 K also show Kondo like behaviour. Our studies support the results of inelastic neutron scattering measurements in PdPr1.5 alloy.
MAGNETIC MOMENT AND HYPERFINE FIELD DISTRIBUTION IN Fe3−xCrxSi ALLOYS
Authors: DOBRZYŃSKI L. , SATULA D. , SZYMAŃSKI K. , WALISZEWSKI J. , MALINOWSKI A. , BRÜCKEL TH. , PRANDL W. , SCHÄRPF O.
Published: November 2004

The magnetization, neutron diffraction and Mössbauer spectroscopy studies have been carried out on Fe3−xCrxSi alloys with x<0.4. It has been shown, that chromium assumes a magnetic moment of the order of one Bohr magneton, ordered antiparallel with respect to the iron magnetic moment. This latter decreases linearly with chromium content. From hyperfine field distribution the probabilities of various local environments and site occupations by Cr were evaluated. The results are compared with neutron data.
LOCAL MAGNETIC ANISOTROPY AND MAGNETOANELASTIC EFFECT IN AMORPHOUS AND NANOCRYSTALLINE ALLOYS
Authors: KRAUS L.
Published: November 2004

Anelastic deformation of amorphous and nanocrystalline metals results in an anisotropic distribution of atomic pair bonds. This mechanism can lead to rather strong macroscopic magnetic anisotropy in some alloys. Experimental results show that the creep-induced magnetic anisotropy of amorphous and nanocrystalline Fe- and Co-based alloys essentially depends both on TM and metalloid elements. This is a clear evidence that the random local magnetic anisotropy in these materials is closely related to the details of electronic structure. Based on this conclusion a model of bond -orientational anisotropy taking into account the distribution of local anisotropies in TM-based alloys is proposed.
STRONG FERROMAGNETISM IN AMORPHOUS FE-NI ALLOYS
Authors: YU M. , KAKEHASHI Y.
Published: November 2004

We elucidate the magnetic properties of amorphous Fe-Ni alloys by combining the geometrical-mean model for the ground-state electronic structure calculations of amorphous alloys with the finite-temperature theory of metallic magnetism. The numerical results show the strong ferromagnetism in the region 0.1≤c≤0.8 and the shift of the Curie-temperature maximum to the higher Fe concentration in agreement with the experimental data. We have clarified that these behaviors are not simply due to the volume change, but due to the change of electronic structure which causes the magnetic energy gain. The agreement between the calculated concentration dependence of effective Bohr magneton number and the experimental data for liquid alloys also supports our theoretical results.
CRITICAL NEUTRON SCATTERING AND ATOMIC SHORT RANGE ORDER IN DILUTE Pd AND Pt BASED ALLOYS
Authors: PARRA R.E. , GONZALEZ A.C.
Published: November 2004

Magnetic neutron scattering data from dilute PtCo, PtFe and PdMn alloys have been analyzed taking into account the presence of critical neutron scattering in these alloys. The unpolarized neutron scattering data shows forward peaks at low K values indicating large magnetization clouds and the presence of critical scattering. The effects of atomic short range order (ASRO) were also included in the analysis of the PtCo alloy. The calculations were made using a magnetic environment model and Monte Carlo simulation methods.
EXPERIMENTAL EVIDENCE FOR SUPERPARAMAGNETISM IN NANOCRYSTALLINE Fe-BASED METALLIC GLASS
Authors: ŚLAWSKA-WANIEWSKA A. , GUTOWSKI M. , LACHOWICZ H.K. , KULIK T. , MATYJA H.
Published: November 2004

Annealing of the initially amorphous Fe66Cr8Cu1Nb3Si9B13 metallic glass above its crystallization temperature leads to the ultrafine crystalline structure of the bcc-FeSi solid solution with a relatively wide distribution of the particle sizes 9≤D≤35 nm. At elevated temperatures the magnetization curves no longer show hysteresis and ideal superparamagnetic behavior is observed. The kinetics of magnetic moment increase during the crystallization process at the time of annealing is also presented.
MAGNETISM OF THE DISORDERED Ni-Fe ALLOY
Authors: LIPIŃSKI S.
Published: November 2004

The magnetic properties of the disordered NixFe1–x alloy are studied by the TB LMTO CPA method using the generalized Stoner picture.
ITINERANT ANTIFERROMAGNETISM IN A FRUSTRATED LATTICE
Authors: LACROIX C. , NUNEZ-REGUEIRO M.D. , BALLOU R.
Published: November 2004

Many different physical situations can be explained by the effect of frustration close to an antiferromagnetic-non magnetic instability. This is the case of several Cerium Kondo lattice compounds, as well as the RMn2 compounds. We propose that these systems can be described within a Blume-Capel model. The influence of frustration is studied analytically and numerically on a triangular lattice: new magnetic ordered phases are obtained in which magnetic and non-magnetic sites are present. The phase diagram is discussed for different values of the exchange interactions.
MAGNETIC RESONANCES IN THE ONE-DIMENSIONAL S=1 SPIN SYSTEM NENP
Authors: PALME W. , KRIEGELSTEIN H. , LÜTHI B. , BRILL T.M. , YOSIDA T. , DATE M.
Published: November 2004

Magnetic resonance experiments in the frequency range 55–404 GHz in magnetic fields up to 14 T are presented. Comparison with an existing field theoretical model leads to gap parameters and critical fields that are only slightly different from those obtained by neutron scattering experiments at q=π. Temperature dependent resonance signal intensities of various branches are compared to calculated intensities in the framework of Boltzmann statistics for temperatures between 1.5 K and 18 K. In this way resonance branches are assigned to transitions within a scheme of energy levels.
ON A QUASI-CLASSICAL THEORY OF ATOMIC PROPERTIES OF SOLID SURFACES
Authors: ZUBOV V.I. , TEIXEIRA RABELO J.N.
Published: November 2004

Equations derived by one of the authors in a preceding paper (Ref. 26) are used to study structural and dynamical surface properties of anharmonic crystals taking into account the first quantum corrections. Anharmonic terms up to the fifth order are included. The lattice relaxation and dynamics near the singular surfaces of a two-dimensional model with square lattice are calculated. Quantum effects on the interplanar thermal expansivity and on the mean-square displacements of atoms are discussed.
SOME CONSIDERATIONS ON THE INFLUENCE OF THE FLEXOELECTRICITY ON THE CRITICAL THICKNESS OF A HYBRID ALIGNED NEMATIC CELL
Authors: ALEXE-IONESCU A.L.
Published: November 2004

We discuss the influence of flexoelectricity on the critical thickness of a hybrid aligned nematic liquid crystal cell, taking into account the surface-like volume elasticity and supposing that the anchoring energy is due only to the dispersion forces. We show that the critical thickness is independent of the flexoelectrical properties of the nematic liquid crystal, and that this conclusion is valid also in the case of generic anchoring energy (dispersion+steric interaction). Furthermore, the possibility of spontaneous Freedericksz transition is shown according to the importance of the elastic coefficient associated to the surface-like volume elasticity with respect to the splay elastic constant.
EINSTEIN-PODOLSKY-ROSEN-BOHM CORRELATION FOR LIGHT POLARIZATION
Authors: MIZRAHI SALOMON S. , MOUSSA MILED H.Y.
Published: November 2004

Considering a classical source of light (macroscopic), we propose an experiment, based on the principles of the Einstein-Podolsky-Rosen-Bohm correlation, for which one expects to obtain the same polarization correlation coefficient as the one predicted by the quantum theory, when photons are counted in coincidence. The results of a numerical simulation give good ground to believe that the conjectured experiment is reasonable. So, one may argue that the property of light called polarization, that is manifest at any level — microscopic and macroscopic — and which has a precise description in both, the quantum and the classical theories, leads to coincident results under correspondingly similar experimental procedures. Therefore the EPRB correlation is a consequence of that property of light, independently whether it is viewed as constituted by photons or by electromagnetic waves.
QUASI-PERIODIC TILINGS OF ORDINARY SPACE
Authors: McMULLEN PETER
Published: November 2004

A method is given for constructing new families of quasi-periodic tilings in ordinary space. These admit inflation and deflation with a factor τ, like those recently constructed by Danzer, and in contrast to the factor τ3 of the Ammann tilings. One of these families is considered in detail, and various of its properties are described. In particular, each tiling in this family possesses six infinite sets of planar sections, which are analogous 2-dimensional tilings. Analogous 4-dimensional tilings are also briefly discussed.
FULL EQUIVALENCE BETWEEN SOCOLAR’S TILINGS AND THE (A, B, C, K)-TILINGS LEADING TO A RATHER NATURAL DECORATION
Authors: DANZER L. , PAPADOPOLOS Z. , TALIS A.
Published: November 2004

In 1986 Socolar and Steinhardt introduced a family of quasiperiodic tilings of the euclidean 3-space E3 by four rhombic zonohedra, which admits a local matching rule. In 1989 the first of the present authors introduced another family with similar properties and four skew tetrahedra A, B, C, K as prototiles. Now we show, that either family can be obtained from the other by a unique construction; hence they are mutually derivable in the sense of Baake et al. Some additional observations are induced by this equivalence.
ELECTRON MICROSCOPY OF QUASICRYSTALS AND THE VALIDITY OF THE TILING APPROACH
Authors: NISSEN H.-U. , BEELI C.
Published: November 2004

A review is presented of high-resolution transmission electron microscopic studies on icosahedral, decagonal and dodecagonal quasicrystals executed during the last eight years, especially at ETH Zürich, with special consideration of the use made of tilings for the interpretation of the electron microscopic image contrast. Since the contrast contains information on the projected potential of the quasicrystal structure, the local details of decorated and undecorated tilings can be correlated to the image contrast. These tilings can even be superimposed directly onto the micrographs as an aid in structural interpretation. Also, tilings can directly be constructed by computer on the basis of contrast maxima or minima appearing in the image. These tilings serve to differentiate between quasiperiodic tiling and random tiling quasicrystal structures. Examples of the successful application of these types of tilings in the structural interpretation of electron microscopic observations on quasicrystal alloys are presented.
BASIC IDEAS OF AMMANN BAR GRIDS
Authors: LÜCK REINHARD
Published: November 2004

The formalism of the Ammann bar grid with two spacings is systematically analyzed. Simple two-by-two matrices describe the self-similar deflation. The deflation and the inflation factors are the two eigenvalues of the matrix. The ratio of the two spacings is derived as another characteristic quantity of the matrices. The maximum number of spacing ratios and the ratios themselves have been derived for a given inflation factor by the matrix formalism. Applications to non-periodic patterns with eightfold, tenfold and twelvefold symmetry are demonstrated. The strong relationship to Fibonacci and Fibonacci related series is explained. The significance of the Ammann bars for matching rules, inflation/deflation procedures and phason movement is outlined.
LATTICE DYNAMICS OF AN F-TYPE ICOSAHEDRAL QUASICRYSTAL
Authors: KASNER G. , BÖTTGER H.
Published: November 2004

By using a matrix-continued fraction approach we calculate the density of vibrational states (DOS) of a tiling model based on the 6D face centered lattice. Parameters of the Lennard-Jones pair interaction are obtained from relaxation calculations. With a ternary decoration the tiling was found to be stable. The DOS was approximated by weighting the local DOS (LDOS) of the allowed vertex configurations by their relative frequencies in the infinite tiling. These frequencies were obtained by using extended deflation rules. Results of this approach are compared to exact finite cluster calculations and an embedded cluster approach. We find the DOS to consist of a single band (in our resolution) and a rich structure at higher frequencies.
TRACE MAPS, INVARIANTS, AND SOME OF THEIR APPLICATIONS
Authors: BAAKE M. , GRIMM U. , JOSEPH D.
Published: November 2004

Trace maps of two-letter substitution rules are investigated with special emphasis on the underlying algebraic structure and on the existence of invariants. We illustrate the results with the generalized Fibonacci chains and show that the well-known Fricke character I(x, y, z)=x2+y2+z2−2xyz−1 is not the only type of invariant that can occur. We discuss several physical applications to electronic spectra including the gap-labeling theorem, to kicked two-level systems, and to the classical 1D Ising model with non-commuting transfer matrices.
ISING CHAIN IN A QUASIPERIODIC MAGNETIC FIELD
Authors: SIRE CLÉMENT
Published: November 2004

This paper is devoted to the study of the ground state properties of an Ising chain in a magnetic Held of the form hi=h sin (ki+ϕ). The ground state energy is exactly computed in various situations. For a given h>2, the ground state energy E(h, k, ϕ) presents local minima as a function of k. This is a mode locking. If h<2, and only for k close enough. to π, the ground state is purely ferromagnetic, the transition being of the first order. As a general feature, the various physical quantities (magnetization, ground state energy…) are shown to be discontinuous at any rational value of k when the ground state is not ferromagnetic. Finally, the rigidity of the ground state under small displacement is also studied. All these results are compared to the ones obtained in a quite similar model: the Frenkel-Kontorova (FK) model. For instance, in our model which is shown to reduce to a constrained FK model, one can observe a lock-in transition, and the critical magnetic field hc(k) is computed, as opposed to the critical potential for the defectible/undefectible transition in the FK case. The hull function is also exactly computed. All these results are illustrated by means of numerical simulations.
SELF-SIMILAR RENORMALIZATION NEAR UNSTABLE FIXED POINTS
Authors: YUKALOV V.I.
Published: November 2004

The method of self-similar approximations for considering strongly interacting systems is generalized by introducing a new parameter called the fixed-point distance. This generalization makes it possible to achieve a high accuracy of the method even in the case of renormalization near unstable fixed points. The consideration is exemplified by calculating an integral with the mathematical structure typical of the partition function of statistical mechanics.
MONTE CARLO CALCULATION OF ORDER-DISORDER PHASE DIAGRAM OF CU-AU
Authors: FAROOQ M. , KHWAJA FARID A.
Published: November 2004

The problem of order-disorder phase transition and phase diagram of the binary copper-gold alloy is analyzed using Monte-Carlo technique. Unlike traditional approaches, the interaction potentials used in our calculations are obtained from the experimental data of diffuse X-ray scattering for the system. The thermodynamic parameters such as configurational energy, specific heat and the order-disorder transition temperatures are calculated directly from the averages of these quantities over many different configurations after an initial equilbration period. The order-disorder phase diagram is constructed and compared with the experimental one, as well as with the results of some previous theoretical approaches.
BEHAVIOR OF VIBRATING PARTICLE BEDS
Authors: Akiyama Testuo
Published: November 2004

This paper describes recent developments in theoretical and experimental studies on the behavior of vibrating particle beds. A parametric study based on a mathematical model, involving isothermal compression of the air within the bed, revealed the effects of vibratory intensity, frequency, bed height and particle size on the behavior of the bed. Experiments indicated that i) the air pressure attained its maximum, over a cycle, at 25 mm from the top of the bed surface and ii) when a tube was immersed in the vibrating bed and held stationary, the surface level of the bed within the tube rose or fell and stabilized at a level different from that of the bed outside the tube.
EXPERIMENTAL STUDY OF BIDIMENSIONAL MODELS OF SAND
Authors: RAJCHENBACH J. , CLÉMENT E. , DURAN J.
Published: November 2004

Experimental investigation on simple model media may shed light on fundamental properties related to the dynamics of dry sand. In our experiments, we use assemblies of monodisperse metallic beads confined in various bidimensional containers. We study the response of these models to a shearing effect in a rotated cylinder and to a vertical vibration. We establish the relevance, on the phenomenology, of microscopic parameters like solid friction and elastic restitution coefficient on collision. We also put emphasise on the influence of the container boundaries. By the mean of an image processing device, we access, in some cases, to the density and to the velocity fields, which allows us to provide a statistical description of a granular flow.
MECHANICAL BEHAVIOR OF POWDER PARTICLE ON THE APPLIED VIBRATION
Authors: Tamura Shigeyuki , Aizawa Tatsuhiko , Kihara Junji
Published: November 2004

Powder is the popular state of material for the many parts of industries. In the powder metallurgy, it is important to know the powder behavior under applied stress for the accurate design and good quality assurance. But the mechanical behaviors of it has not been well known. We consider this is from the difficulty of handling powder numerically. To investigate the fundamental mechanism of powder behaviors, we performed experiment and numerical analysis for the powders on the applied vibration. In this experiment specimens of powder are on the vertical vibrator. And the dynamic location of powder particle are observed by a laser-displacement meter, at the same time dynamic flow of powder are observed by a high-speed video camera. From this experiment we found that the powder flow can be classified to several patterns and those patterns are strongly depending on the frequency and amplitude of applied vibration, particle size, and grain size distribution of the powder. In the numerical analysis we used the particle model. This calculation model refer to Cundall’s Distinct Element Method. We performed several numerical analysis on various conditions. From the result we considered the major parameter which determine the flowing pattern is the frictional conditions.
Cell-Dynamics Modeling of Vibrating Powder
Authors: Oono Yoshitsugu
Published: November 2004

The instabilities in vibrating granular materials may be interpreted as segregation processes of vacuum and powder particles. Through an attempt of mesocale modeling of the instabilities within the cell-dynamics scheme, a notable distinction between the ordinary segregation processes such as binary alloy spinodal decomposition and the granular processes is highlighted. ‘Vibrating particles in a horizontal Hele-Shaw cell’ experiment is proposed.
ONE YEAR HOURGLASS FROM THE PROSPECT OF PARTICLES
Authors: SHIWA YASUMARO , WONG YU
Published: November 2004

We construct huge hourglass which works over one year. The condition in order to maintain smoth flow of sand is explained. Many unexpected phenomena are observed and must be solved in order to get smoth flow.
QUANTUM STATE CONTROL IN SEMICONDUCTOR pn JUNCTIONS (III) — COULOMB BLOCKADE OF RESONANT TUNNELING IN pn MICROJUNCTIONS
Authors: IMAMOḠLU A. , YAMAMOTO Y.
Published: November 2004

We show that Coulomb blockade of resonant tunneling in semiconductor heterojunctions creates correlations between single-charge tunneling and single-photon emission events. The single electron (hole) charging energy has to exceed the characteristic energy of the thermal fluctuations, for these correlations to be observable. The light field generated by the analyzed mesoscopic heterostructure is inherently nonclassical. The effects of quantum confinement and possible applications of the single-electron/single-photon manipulation techniques are discussed.
BROKEN TIME-REVERSAL SYMMETRY AND BERRY’S PHASE
Authors: IHM JISOON
Published: November 2004

Berry’s phase is typically realized in a system consisting of fast and slow variables, when the trajectory of the slow variable makes a closed loop. The quantum mechanical phase picked up by the fast variable while the slow variable traverses the loop has turned out to produce real physical effects through quantum interference. In this article, we investigate origins of Berry’s geometric phase and show that they are in general attributable to the broken time-reversal symmetry of the system. Our analysis leads to the classification of Berry’s phase for Hamiltonian systems in terms of symmetry properties under time-reversal operations. Spontaneous time-reversal symmetry-breaking of state vectors is shown to give rise to Berry’s phase as exemplified by a quantum-mechanical rotated hoop. A system with an explicitly time-reversal symmetry-breaking Hamiltonian is also demonstrated to exhibit nontrivial Berry’s phase. The quantization of the geometric phase associated with the real two-dimensional Hamiltonian having topological singularity is explained within the same framework. The unique role of the time-reversal operator among general antiunitary operators is also discussed.
INVARIANCE OF THE GENERALIZED HANNAY ANGLE UNDER GAUGE TRANSFORMATIONS: APPLICATION TO THE TIME-DEPENDENT GENERALIZED HARMONIC OSCILLATOR
Authors: KOBE DONALD H.
Published: November 2004

The Hannay angle of classical mechanics is generalized so that it is invariant under gauge transformations, which are a restricted class of canonical transformations. A distinction between the Hamiltonian and the energy is essential to make in time-dependent problems. A time-dependent generalized harmonic oscillator with a cross term in the Hamiltonian is taken as an example. The Hamiltonian of this system is not in general the energy. The energy, the time derivative of which is the power, is obtained from the equation of motion and related to the action variable. Hamilton’s equations give the time rate of change of the angle and action variables. The generalized Hannay angle is shown to be zero, and remains invariant under gauge transformations. On the other hand, if the original Hamiltonian is chosen as the energy, a nonzero generalized Hannay angle is obtained, but the power is given incorrectly. Nevertheless in the adiabatic limit, the total angle, which is the sum of the dynamical and Hannay angles, is equal to the one calculated from the correct energy.
NEUTRAL AND CHARGED ANYON FLUIDS
Authors: HOSOTANI YUTAKA
Published: November 2004

Properties of neutral and charged anyon fluids are examined, with the main focus on the question of whether or not a charged anyon fluid exhibits a superconductivity at zero and finite temperature. Quantum mechanics of anyon fluids is precisely described by Chern-Simons gauge theory. The random phase approximation (RPA), the linearized self-consistent field method (SCF), and the hydrodynamic approach employed in the early analysis of anyon fluids are all equivalent. Relations and differences between neutral and charged anyon fluids are discussed. It is necessary to go beyond RPA and the linearized SCF, and possively beyond the Hartree-Fock approximation, to correctly describe various phenomena such as the flux quantization, vortex formation, and phase transition.
PULSED SUPERRADIANT EMISSION FROM A MAGNETIC DIPOLE SYSTEM
Authors: MIZRAHI SALOMON S. , MEWES MAURO A.
Published: November 2004

The superradiant emission is considered for a radiating system constituted by N dressed spin-1/2 magnetic dipoles, described by a nonlinear single particle Hamiltonian that is derived under a mean field approximation. This Hamiltonian describes adequately the transient regime of the emission process: The intensity of the radiation follows the sech2 law and its peak is proportional to N2. Then, one considers the application of a periodic time-dependent transverse magnetic field and we study the behavior of the emission that becomes periodically pulsed.
METAL-INSULATOR TRANSITIONS AND STRONG ELECTRON CORRELATIONS
Authors: MICHIELSEN KRISTEL
Published: November 2004

An overview of lattice models for strongly correlated electrons is given. A detailed study is presented of a model recently introduced by Montorsi and Rasetti. Analytical, exact diagonalization and Quantum Monte Carlo techniques are employed to investigate the static and dynamic properties of this model. The complete ground state phase diagram of the one-, two- and three-dimensional model is given. The Montorsi-Rasetti model is shown to exhibit a metal-insulator transition of the Mott type, independent of the dimensionality of the lattice, and has a ferromagnetic phase. Results for the two-dimensional Montorsi-Rasetti model strongly suggest the occurrence of a phase transition at finite temperatures.
HIERARCHICAL WAVE FUNCTIONS OF FRACTIONAL QUANTUM HALL EFFECT ON THE TORUS
Authors: LI DINGPING
Published: November 2004

One kind of hierarchical wave functions of Fractional Quantum Hall Effect on the torus is constructed. We find that the wave functions are closely related to the wave functions of generalized Abelian Chern-Simons theory.
DYNAMICAL STRUCTURE FACTOR FOR s-f MODEL WITH AN EXTERNAL MAGNETIC FIELD BELOW Tc
Authors: WESSELINOWA J.M. , YORDANOVA M.G.
Published: November 2004

The dynamical structure factor for the s-f model with an applied magnetic field is investigated using a Green function technique. The peak broadening is remarkable in a low field whereas in a high field the peak broadening mechanism is almost suppressed. This is in agreement with the experimental data for the europium chalcogenides EuS and EuSe.
HIERARCHICAL WAVE FUNCTIONS AND FRACTIONAL STATISTICS IN FRACTIONAL QUANTUM HALL EFFECT ON THE TORUS
Authors: LI DINGPING
Published: November 2004

One kind of hierarchical wave functions of Fractional Quantum Hall Effect (FQHE) on the torus are constructed. The multi-component nature of anyon wave functions and the degeneracy of FQHE on the torus are very clearly reflected in this kind of wave functions. We also calculate the braid statistics of the quasiparticles in FQHE on the torus and show they fit the picture of anyons interacting with magnetic field on the torus obtained from braid group analysis.
E(K) OF Ni ABOVE THE VACUUM LEVEL AS MEASURED BY VLEED ON RELAXED (110) SURFACE
Authors: STROCOV V.N.
Published: November 2004

Varying incidence angle, VLEED spectra R(E) and dR/dE were measured on Ni(110) using target current technique. The results were interpreted with the reference spectra calculated on the basis of ground-state band structure. Some critical points (CPs) of E( k ) displayed themselves as dR/dE extremums while others remained invisible. Changing of incidence K || by a surface reciprocal vector switched manifesting CPs. Experimental CPs were determined by comparing energies of experimental dR/dE extremums with. their reference counterparts. Having mapped CPs along a variety of non-symmetry directions, bands along ΓX were constructed. Experimental E( k ) is consistent with other experimental data and APW calculations. Some peculiarities are attributed to the influence of surface relaxation. Capabilities of VLEED to provide PES with upper bands are discussed.
ELECTRONIC CORRELATIONS AND ELECTRON-PHONON COUPLING IN C60
Authors: SALKOLA MARKKU I. , CHAKRAVARTY SUDIP , KIVELSON STEVEN A.
Published: November 2004

We study a model of a single molecule of C 60 to obtain an understanding of the interplay between the electron-electron and electron-phonon interactions in these molecules. In particular, we calculate the intramolecular phonon spectrum, infrared intensities, and the Raman intensities. We also find that when correlation effects are sufficiently strong, the Jahn-Teller distortion of the doubly charged molecule is suppressed. Thus, if the correlation effects are strong, the superconductivity in doped C 60 cannot be mediated by intra-molecular Jahn-Teller phonons.
STUDY OF SLOW DYNAMICAL PROCESSES BY NEUTRON-SPIN-ECHO
Authors: MEZEI FERENC
Published: November 2004

Conventional resolution inelastic neutron scattering spectroscopy allows us to explore the behaviour of condensed matter essentially on the time scale of thermal atomic vibrations. By the application of the Neutron Spin Echo trick, which enables us to get around the Liouville theorem limitation of conventional methods, the resolution can be improved very substantially. This opened up the field for the study of a large variety of slow motion phenomena (critical slowing down, relaxation effects, disordered dynamics, soft matter), i.e. the investigation of processes on a mesoscopic time scale between microscopic collision times and macroscopic dynamics.
NEUTRON DIFFRACTION AND RMC MODELLING: COMPLEMENTARY TECHNIQUES FOR THE DETERMINATION OF DISORDERED STRUCTURES
Authors: McGREEVY R.L.
Published: November 2004

The use of neutron diffraction and RMC modelling in the determination of the structures of disordered materials is described. The principle of the method is outlined and then illustrated by examples including monatomic and binary liquids, molecular liquids, solutions and metallic glasses. The application to the determination of magnetic structures in disordered materials is also shown. Finally the extension to enable the combination of neutron and X-ray data, and possible future developments, are discussed.
MULTIPLE-Q STRUCTURES IN FRUSTRATED ANTIFERROMAGNETS
Authors: LONG M.W.
Published: November 2004

The concepts relevant to frustrated antiferromagnets are briefly reviewed. Antiferromagnets are classified according to their symmetry groups, with non-trivial point groups leading to the possibility of multiple-Q antiferromagnetism. The role of residual degeneracy is highlighted and the manner in which this degeneracy is lifted is discussed. The physical phenomena in competition within frustrated magnets, and the states that they prefer, yield ongoing theoretical research, and the way neutron scattering can be used, in conjunction with the application of pressure and magnetic fields, to determine which of the possible magnetic structures is stabilised is under experimental scrutiny. Multiple-Q antiferromagnetism finds varied and often exotic spin states with similar energies, and as such is the setting in which phase transitions between different magnetic states can be studied.
NEUTRON POWDER DIFFRACTION AND OXIDE SUPERCONDUCTORS
Authors: HEWAT A.W.
Published: November 2004

Neutron powder diffraction has been essential for understanding the structures of the new high temperature oxide superconductors because of the difficulty in locating oxygen with X-rays in the presence of heavy metals, especially when single crystals are usually not available. This understanding lead to the discovery of new materials. In this paper we will show how it also sheds light on the crystal chemistry of oxide superconductors—the effects of oxidation/reduction, phase separation, pressure etc.
DIFFUSION OF A HEAVY PARTICLE IN A FERMI-LIQUID THEORY
Authors: PROKOF’EV N.V.
Published: November 2004

This article reviews the recent work in quantum diffusion of particles interacting with the Fermi-liquid environment. Two distinct problems discussed are: (a) the dynamics of a heavy particle in a homogeneous Fermi-liquid (which is the case of ion motion in normal liquid 3 He ) and (b) the tunneling diffusion of particles in metals in the presence of strong crystal potential. Attention is given to the strong interaction effects which in most cases lead to the particle quasilocalization (localization) and destroy the coherent propagation of particles down to extremely low temperatures. The overdamped particle motion, mass renormalization and fermionic polaron effect are discussed in detail. Some attention is also given to the experimental investigations in this field, concentrating particularly on ion mobility in 3 He and muon (hydrogen) diffusion in metals.