Showing papers in "Journal of Physics: Condensed Matter in 1989"
TL;DR: In this article, it was shown that the equation of state for all classes of solids in compression can be expressed in terms of a universal function, and that the form of this universal function is determined by scaling experimental compression data for measured isotherms of a wide variety of Solids.
Abstract: A study of the energetics of solids leads to the conclusion that the equation of state for all classes of solids in compression can be expressed in terms of a universal function. The form of this universal function is determined by scaling experimental compression data for measured isotherms of a wide variety of solids. The equation of state is thus known (in the absence of phase transitions), if zero-pressure volume and isothermal compression and its pressure derivative are known. The discovery described in this paper has two immediate consequences: first, despite the well known differences in the microscopic energetics of the various classes of solids, there is a single equation of state for all classes in compression; and second, a new method is provided for analyzing measured isotherms and extrapolating high-pressure data from low-pressure (e.g. acoustic) data.
847 citations
TL;DR: In this article, Car and Parrinello proposed a pseudopotential method for calculating the vacancy energy in simple metals and presented results for aluminium, based on the local density approximation for exchange and correlation, and periodically repeating geometry.
Abstract: This paper addresses the problem of calculating the vacancy formation energy in simple metals and presents results for aluminium. The calculations are based on the pseudopotential method, the local-density approximation for exchange and correlation, and periodically repeating geometry. The approach used is similar to that proposed by Car and Parrinello, and allows the simultaneous relaxation of the electrons and the ionic positions. Problems peculiar to metals in this approach are discussed and a way of overcoming them is presented. The calculated vacancy energy (0.56 eV) in aluminium is in quite good agreement with experiment (0.66 eV). Comparisons with perturbation theory show that the calculated value is subject to a technical error of only approximately 0.03 eV and that corrections due to periodic boundary conditions are also of this order. The contribution to the vacancy energy from non-linear effects is similar to the jellium estimate of Evans and Finnis.
386 citations
TL;DR: In this paper, the authors review the arguments for this behaviour based on field-theory mappings, the Lieb-Schultz-Mattis theorem, exactly solvable models, finite-chain diagonalisation and real experiments.
Abstract: One-dimensional antiferromagnets have exotic disordered ground states. As was first argued by Haldane (1983), there is an excitation gap for integer, but not half-integer, spin. The authors review the arguments for this behaviour based on field-theory mappings, the Lieb-Schultz-Mattis theorem, exactly solvable models, finite-chain diagonalisation and real experiments.
363 citations
TL;DR: In this paper, a simple expression for the dependence of the quantised conductance on the width of the wide region is given, and a distinction between experiments and discussions that are strictly limited to events at reservoirs and, on the other, those that have a concern with variations within the sample.
Abstract: The domain of validity and the origin of different formulae relating conductance to transmissive behaviour is discussed. The large variety of possible measurement probes is emphasised. The quantised conductance of constrictions, studied in recent experiments, is treated. Theoretical discussions of that have stressed the supposedly unique role of G = (2e2/h)Tr(tt†) in this connection, regardless of the exact geometry or probe locations. This is shown to be incorrect, and a simple expression for the dependence of the 'quantised' conductance on the width of the wide region is given. We particularly emphasise the distinction between, on the one hand, experiments and discussions that are strictly limited to events at reservoirs and, on the other, those that have a concern with variations within the sample.
349 citations
TL;DR: In this paper, the electron energy loss and X-ray absorption spectra of two phases of titanium dioxide-rutile and anatase-were reported, and the authors proposed an interpretation of the Ti L2.3 edge, notably for the presence of a previously unobserved splitting on the L3 edge.
Abstract: The electron energy loss and X-ray absorption spectra of two phases of titanium dioxide-rutile and anatase-are reported. Although the nearest-neighbour environments of titanium and oxygen in both these structures are very similar, noticeable differences are observed between the electron energy loss and the X-ray absorption spectra. Attempts to model these differences using real-space multiple-scattering calculations are reasonably successful at the Ti K and O K edges. The authors propose an interpretation of the Ti L2.3 edge, notably for the presence of a previously unobserved splitting on the L3 edge.
311 citations
TL;DR: The magnetic ordering of a single crystal of the cubic polymorph of FeGe has been studied by small-angle neutron scattering as discussed by the authors, and the magnetic ordering in cubic FeGe is a Dzyaloshinskii spiral similar to the structure observed in the compound MnSi.
Abstract: The magnetic ordering of a single crystal of the cubic polymorph of FeGe has been studied by small-angle neutron scattering. The compound orders magnetically at TN=278.7 K into a long-range spiral (period approximately 683-700 AA) propagating along equivalent directions at high temperatures and along equivalent directions at low temperatures. The length of the spiral wavevector is nearly independent of temperature. The transition at TN is first order with very little hysteresis. The transition at which the direction of the spiral turns is rather sluggish. It takes place in a temperature interval of approximately 40 K and shows pronounced temperature hysteresis (T2 down arrow =211 K, T2 up arrow =245 K). Applied magnetic fields of 20-40 mT, depending on the temperature and the field direction, cause the spiral axis to turn into the direction of the applied field. As the field is further increased, the amplitude of the antiferromagnetic spiral decreases and the ferromagnetic component increases until at fields above approximately 200-300 mT cubic FeGe becomes magnetically saturated. The magnetic ordering in cubic FeGe is a Dzyaloshinskii spiral similar to the structure observed in the isostructural compound MnSi. However, in MnSi the spiral propagates along equivalent directions at all temperatures below TN=29.5 K.
246 citations
TL;DR: In this paper, a fast KKR CPA method is explained and its convergence properties are examined numerically, and it is shown that a step number of N 300, which determines the number of k-points used for the numerical integration in the k-space as well as a number of iteration steps in determining the coherent t-matrix, is sufficient for most purposes, including total energy calculations.
Abstract: A fast KKR CPA method is explained and its convergence properties are examined numerically. It is shown that a step number of N 300, which determines the number of k-points used for the numerical integration in the k-space as well as the number of iteration steps in determining the coherent t-matrix, is sufficient for most purposes, including total-energy calculations. As a typical application the electronic structure of ferromagnetic Ni-Fe systems is calculated in the framework of the KKR CPA combined with the local spin density approximation, which demonstrates the feasibility of the present method.
234 citations
TL;DR: In this paper, the spin reorientation transitions for rare earths with a negative second-order Stevens coefficient alpha J(Nd, Tb, Dy) were derived to account for the transitions in a consistent way.
Abstract: Magnetic properties of the series of ThMn12-structure intermetallic compounds R(Fe11Ti) have been determined for rare earths from Nd to Lu plus Y. The highest Curie temperature (607 K) is for R=Gd, and R-Fe exchange interactions are much stronger for light rare earths than for heavy ones. The temperature dependence of the iron sublattice magnetisation and anisotropy are determined for the Y and Lu compounds. Spin reorientation transitions are found as a function of temperature for the rare earths with a negative second-order Stevens coefficient alpha J(Nd, Tb, Dy), and a set of crystal-field parameters is derived to account for the transitions in a consistent way. A sharp increase in magnetisation observed for Sm(Fe11Ti) below 130 K in a field of about 10 T applied perpendicular to the easy direction indicates that J-mixing may be important for Sm3+. Compared with R2Fe14B, the iron anisotropy in R(Fe11Ti) is greater, and the rare-earth anisotropy is much weaker at low temperature, with the opposite sign for the rare-earth crystal-field coefficient A20. The average iron moment is 1.7 mu B in R(Fe11Ti) at 4.2 K; Mossbauer spectra are analysed to yield the average moments on each site. Limits set by the intrinsic magnetic properties on the performance of magnets made from these families of alloys are discussed.
226 citations
TL;DR: In this article, the positron affinity is defined as the sum of the Fermi level and the bottom of the lowest positron band relative to a common, well-defined reference energy.
Abstract: The relevant quantity in the comparison of the absolute positron energy levels in different materials is the sum of the internal electron and positron chemical potentials, i.e. the sum of the Fermi level and the bottom of the lowest positron band relative to a common, well-defined reference energy. This sum is defined as the positron affinity. The positron affinity reflects the preference of the positron for different components in heterostructures made of different materials and the preference between the host matrix and precipitates in alloys. Moreover, the affinity is closely related to the positron work function and positronium formation potential which are important parameters in the slow-positron-beam experiments. The authors have determined the positron affinity for the alkaline and alkaline-earth metals, 3d-, 4d-, and 5d-transition metal series, and for some metals on the right in the Periodic Table. The diamond structure semiconductors are also considered. The determination is based on the self-consistent electron structure calculations and the subsequent calculation of the positron band structure within the local-density approximation. The trends are studied and interpreted along the different columns and rows of the Periodic Table. The results are also compared with available experiments.
203 citations
TL;DR: In this article, the electrical transport properties of one-dimensional tight-binding models, with correlation between diagonal and off-diagonal disorder, are obtained using Felderhof's method, and a new local transformation eliminating the off-dimagonal disorder is utilised.
Abstract: The electrical transport properties of one-dimensional tight-binding models, with correlation between diagonal and off-diagonal disorder, are obtained using Felderhof's method. A new local transformation eliminating the off-diagonal disorder is utilised. The characterisation of the type of correlation for the existence of a critical energy Ec, at which transmission exists, is found. It is a generalisation, in some sense, of the well known transmission at the band centre for the case with only off-diagonal disorder. For the high-wavenumber approximation we find explicitly the inverse localisation length which, close to Ec, behaves as mod E-Ec mod nu , with nu =1 at the edges of the band and nu =2 otherwise. The transmission for a wavepacket around Ec is analysed for samples of finite size.
161 citations
TL;DR: In this article, the magnetic structure of the cubic gamma-Fe100-xCox (x < 4) alloy precipitates is studied by neutron diffraction, and spin-density wave (SDW) propagating along the cubic axis is found for these specimens.
Abstract: An X-ray diffraction study reveals that an introduction of a small amount of Co suppresses the structural phase transition of gamma -Fe precipitates in Cu and the cubic gamma -FeCo alloy precipitates are available even at the lowest temperature. The magnetic structure of the cubic gamma -Fe100-xCox (x<4) alloy precipitates is studied by neutron diffraction, and spin-density wave (SDW) propagating along the cubic axis is found for these specimens. The Neel temperature and wavelength of the SDW decrease with increasing Co concentration. It is demonstrated that the magnetic structure of the cubic gamma -Fe precipitates is also the SDW state.
TL;DR: In this article, the magnetic properties of the chromium tellurides were analyzed and the Hall effect was used to show that the spin structure is not collinear ferromagnetic above Ts.
Abstract: Electronic band-structure calculations are presented for the ferromagnetic compounds CrTe, Cr3Te4 and Cr2Te4 and Cr2Te3. In these compounds the Cr3d-Te5p covalency and the Cr3d(z2)-Cr3d(z2)-overlap along the c axis are the most important interactions. The magnetic polarisation of Te is parallel to the Cr local moment in CrTe, antiparallel to it in Cr2Te3 and about zero in Cr2Te4. Measurements of electronic transport properties (resistivity, Hall effect and thermo-electric power) and magnetic properties of Cr1- delta Te( delta =0.1) and Cr3+xTe4(x=0.2) indicate that these chromium tellurides are p-type metals, with strong interaction between the holes in the Te5p band and the Cr magnetic moments. In the literature the variation of the magnetic properties of Cr3.2Te4 near Ts approximately=100 K has been attributed to a change from a canted antiferromagnetic to a collinear ferromagnetic structure. However, our Hall-effect measurements indicate that the spin structure is not collinear ferromagnetic above Ts.
TL;DR: In this article, the first-order difference method of isotopic substitution has been used to obtain the local structure around Ag(aq)+ in heavy water, and the results have been used in conjunction with those from an X-ray diffraction study of 3.1 M (molar) AgNO3 and NaNO3.
Abstract: Neutron diffraction experiments have been conducted on 3.1 M (molar) solutions of 107AgNO3 and 109AgNO3 in heavy water, and the first-order difference method of isotopic substitution has been used to obtain the local structure around Ag(aq)+. The results of this work have been used in conjunction with those from an X-ray diffraction study of 3.1 M (molar) AgNO3 and NaNO3, to establish the degree of structural isomorphism between Na(aq)+ and Ag(aq)+. It has been shown that Na(aq)+ and Ag(aq)+ are sufficiently isomorphic to enable useful pictures to be obtained for both Na+ hydration and Ag+-Ag+ coordination. Comparison with previous results for the other alkali metal ions shows that, in terms of the strength of hydration, Na+ is intermediate between Li+ and K+.
TL;DR: In this paper, the structural slowing down in a binary alloy of soft spheres near the fluid-glass transition has been investigated by extensive molecular dynamics simulations, and an attempt is made to characterise the transition on the basis of r- and k-space representations of the incoherent and coherent parts of the density autocorrelation functions.
Abstract: The structural slowing down in a binary alloy of soft spheres near the fluid-glass transition has been investigated by extensive molecular dynamics simulations. An attempt is made to characterise the transition on the basis of r- and k-space representations of the incoherent and coherent parts of the density autocorrelation functions. A careful analysis of the Van Hove functions allows the authors to put forward two novel diagnostics of the underlying 'ideal' glass transition, which yield the same value of the critical glass transition temperature. The latter appears to be independent of the mass ratio of the two species in the mixture. The damping of the longitudinal sound mode at the longest accessible wavelength appears to be surprisingly independent of temperature, while the damping of the corresponding transverse sound mode decreases significantly as the temperature is lowered.
TL;DR: In this article, an SU(2) path integral formulation of a Kondo lattice model for heavy fermions is proposed, which treats the RKKY interaction explicitly and finds the heavy Fermi liquid becomes unstable to the formation of a spin liquid amongst the f spins.
Abstract: The authors consider an SU(2) path integral formulation of a Kondo lattice model for heavy fermions that treats the RKKY interaction explicitly At low temperatures they find the heavy Fermi liquid becomes unstable to the formation of a spin liquid amongst the f spins Kondo coupling to the spin liquid stabilises it against antiferromagnetism, causing the resonating valence bonds of the spin liquid to occasionally escape into the conduction sea This process induces off-diagonal resonant scattering in the conduction sea, thereby generating anisotropic superconductivity in the heavy fermion system
TL;DR: In this article, the role of quasilowdimensionality for delocalized electrons was stressed, and the potential superiority of fine mesh three dimensional networks of chain conductors argued from that point of view.
Abstract: Classical BCS superconductive couplings leading to small Tc‘s rely on phonon mediated weak coupling of delocalized electrons in three dimensional structures. Attempts to produce or explain higher Tc have considered the breakdown of one or several of these hypotheses. The possible role of quasilowdimensionality for delocalized electrons will be stressed, and the potential superiority of fine mesh three dimensional networks of chain conductors argued from that point of view.
TL;DR: In this article, a theoretical study of the (111) surfaces of the face-centred cubic transition and noble metals iridium, platinum and gold is reported, and the surface stress tensor and surface energy of the unreconstructed surfaces of each of these materials has been calculated using the pseudopotential total energy method.
Abstract: A theoretical study of the (111) surfaces of the face-centred cubic transition and noble metals iridium, platinum and gold is reported. The surface stress tensor and surface energy of the unreconstructed (111) surfaces of each of these materials has been calculated using the pseudopotential total energy method. In each case the surface stress is tensile, with the stress for gold being the smallest. The implications of these results for surface stability are discussed.
TL;DR: In this article, the elastic energy originating from the direct elastic interaction between the high-spin and low-spin complex molecules randomly distributed over the lattice sites is computed, and the crystal is considered as an isotropic homogeneous elastic medium with the spin-changing ions as point defects described by elastic dipole tensors PHS and PLS.
Abstract: For pt.I see ibid., vol.21, p.1423 (1988). Several transition-metal compounds show a transition from the low-spin to the high-spin electronic state with increasing temperature. The cooperative nature of the transition in the solid state is attributed to the elastic interaction between the spin-changing ions as a result of the deformation of the crystal accompanying the transition. In a previous work the long range part of the elastic interaction due to the image pressure on a spherical surface was treated. In this work the elastic energy originating from the direct elastic interaction between the high-spin and low-spin complex molecules randomly distributed over the lattice sites is computed. The crystal is considered as an isotropic homogeneous elastic medium with the spin-changing ions as point defects described by elastic dipole tensors PHS and PLS, respectively. The interaction depends on the components of the tensor difference PHL=PHS-PLS which are unequivocally determined based on the X-ray data of the compounds (Fe(2-pic)3) Cl2.Sol (2-pic=2-aminomethylpyridine, Sol=MeOH, EtOH). Collecting both contributions (the image and the direct part) the value of the interaction constant Gamma can be explained in a consistent way for both compounds.
TL;DR: In this article, self-consistent energy band calculations for LuFe2 are reported and the calculated moment is 2.85 mu B/formula unit in agreement with experiment.
Abstract: Self-consistent energy band calculations for LuFe2 are reported. LuFe2 is found to order magnetically according to the Stoner criterion and the calculated moment is 2.85 mu B/formula unit in agreement with experiment. Spin-orbit coupling was included in the calculation and the spin and induced orbital contributions to the moment at the Fe site also found to be in agreement with experiment. The total moment is calculated to include a contribution of -0.41 mu B at the Lu site, which as yet has not been observed. The mechanism responsible for the ferrimagnetic alignment of the 3d and 5d spin densities is investigated in detail, and the Lu-5d moment related to 3d-5d hybridisation.
TL;DR: The first sharp diffraction peak in binary metallic glasses is distinguished from the pre-peak in binary metal glasses, which occurs at higher wavevectors when scaled in this way as discussed by the authors.
Abstract: Many glasses and liquids exhibit a first sharp diffraction peak that is evidence for intermediate-range order caused by regularities in the packing of structural units. These tend to cluster around particular values of the wavevector when scaled by the nearest-neighbour distance or the mean inter-atomic spacing. The first sharp diffraction peak is distinguished from the pre-peak in binary metallic glasses, which occurs at higher wavevectors when scaled in this way.
TL;DR: In this article, the authors present a model for conduction in disordered systems by variable-range tunnelling in a Coulomb gap, and show that the model cannot apply to these systems.
Abstract: The author sets out the model for conduction in disordered systems by variable-range tunnelling in a Coulomb gap. Detailed analysis of experimental data for three different types of granular metal shows that the model cannot apply to these systems. He concludes that the problem of the mechanism of conduction in granular metals remains unsolved.
TL;DR: In this paper, the authors predict a new type of conductance oscillations in a GaAs heterostructure with a strip-like gate with a hole, which defines a conducting dot (under the hole) in an otherwise depleted region of a two-dimensional electron gas.
Abstract: The authors predict a new type of conductance oscillations in a GaAs heterostructure with a proposed strip-like gate with a hole. Such a gate defines a conducting dot (under the hole) in an otherwise depleted region of a two-dimensional electron gas. The oscillations are caused by discrete changes of the charge of the dot as the gate voltage is varied. They show that for low temperatures, T
TL;DR: In this paper, the authors present a model for the superconducting states of UPt3 in which a two-dimensional order parameter couples to a field that breaks the hexagonal symmetry of the crystal.
Abstract: The authors present a model for the superconducting states of UPt3 in which a two-dimensional order parameter couples to a field that breaks the hexagonal symmetry of the crystal. This symmetry-breaking field (SBF) splits the superconducting transition, leading to two superconducting phases in zero field. The high-temperature superconducting phase exhibits the broken hexagonal symmetry of the SBF, while the low-temperature phase spontaneously breaks time-reversal symmetry. The authors calculate the specific heat jumps at both transitions and compare with the recent measurements by Fisher et al. They find that sizeable strong-coupling corrections are needed to explain the magnitude of the heat capacity jumps and the splitting of the transition. They show that a kink in the upper critical field occurs for fields in the basal plane. Comparison of the discontinuity in the slope of Hc2(T) with the data of Taillefer et al. (on a different UPt3 crystal) is in qualitative agreement with the heat capacity data. They also predict a change in slope of Hcl(T) at the temperature of the second peak in the heat capacity, for all field orientations. Observation of all three features in the same single crystal would provide convincing evidence for unconventional pairing in UPt3 and would be a stringent test of the model presented.
TL;DR: In this paper, the important parameters (electron mean free path versus contact dimension) in point-contact spectroscopy are discussed together with examples of spectroscopic information obtained in various systems.
Abstract: Micro-contacts between metals at low temperatures reveal non-linear structures in the current-voltage characteristics. These deviations from Ohm's law allow an energy-resolved spectroscopy of the interaction of the conduction electrons with elementary excitations (e.g. phonons) in a metal. To explain the method, the important parameters (electron mean free path versus contact dimension) in point-contact spectroscopy will be discussed together with examples of spectroscopic information obtained in various systems. Local temperature gradients in the contact region offer the possibility to study thermo-electric phenomena in small constrictions, such as thermal voltages in non-homogeneous contacts and quenching of the phonon-drag term in the thermo-power in homogeneous contacts. Besides these aspects of the point-contact technique, recent experiments will be shown with applications of point contacts other than just spectroscopy: magneto-resistance of a point contact, high-frequency rectification with a point contact as the non-linear element, electron focusing using a double point-contact set-up, electrical noise in constrictions and generation of phonons by means of point contacts.
TL;DR: The topological Chern-Simons term with the parameter theta =n pi exists in the superfluid 3He-A thin film, where an integer parameter n may be odd or even depending on the thickness of the film.
Abstract: The topological Chern-Simons term with the parameter theta =n pi exists in the superfluid 3He-A thin film, where an integer parameter n may be odd or even depending on the thickness of the film. The particle like soliton in 3He-A film (so-called skyrmion) with integer topological charge Q has spin s=nQh(cross)/2 and obeys Fermi-Dirac quantum statistics at odd Q and n. The topological term in action leads to specific quantised Hall effect for spin current in 3He-A. In the planar phase of the 3He film the non-singular 4 pi spin disclination has the fractional fermion charge 1/2n which corresponds to the fractional electric charge 1/2en for the disclination in the planar state superconductor. The spin disclination in the 3He-A1 film has both the fractional spin 1/4h(cross)n and fractional charge 1/4n.
TL;DR: In this paper, a series expansion for the inelasticity corrections has been calculated to higher order than has been done before and it is shown that the new terms are significant.
Abstract: The authors discuss in detail the analysis of structural data on liquids obtained using time-of-flight neutron diffractometry, in particular the Liquids and Amorphous Materials Diffractometer (LAD) situated at the ISIS pulsed neutron source at the Rutherford Appleton Laboratory. A series expansion for the inelasticity corrections has been calculated to higher order than has been done before and it is shown that the new terms are significant. It is argued, however, that there are fundamental reasons why any such correction will be inadequate for the lowest-energy neutrons. The problem of combining the results from detectors at different angles is considered and the authors present a generally applicable method for doing this in such a way that the effect of instrumental resolution is readily included. These procedures are demonstrated and tested on data obtained in an experiment to measure the structure factor of molten CsCl at 670 degrees C, close to the melting point, and at 970 degrees C using LAD. The result at the lower temperature is in good agreement with a previous result obtained using the D4 steady state diffractometer at the High Flux Reactor of the Institut Laue-Langevin, Grenoble. The change in the structure factor between the two temperatures can be accounted for entirely in terms of density scaling indicating that there is little, if any, change in the pair correlation function g(r) as the temperature is raised.
TL;DR: In this article, angle-resolved photoemission was used to investigate the 4f valence band and shallow core levels of ultrathin Gd overlayers on Cu(100) and on crystalline nickel overlayers in the presence of Gd5d and 5p eigenstates.
Abstract: The 4f valence band and shallow core levels of ultrathin Gd overlayers on Cu(100) and on crystalline nickel overlayers on Cu(100) have been investigated using angle-resolved photoemission. The authors have observed a definite selection of final-state symmetries which, for one-half to four-monolayer-thick Gd films, indicates that the occupied Gd 5d band is predominantly 3z2-r2 and j=3/2 in character. The 5p3/2 appears to be predominantly z in character for thin Gd overlayers on Cu(100). This occurs as a consequence of final-state interactions between the Gd5d and 5p eigenstates. These results, together with the observed screening processes of the photoemission hole state, are discussed and applied to the understanding of photoemission resonance from the valance bands.
TL;DR: In this article, the mode-coupling theory of the liquid-glass transition is applied to the hard-sphere system and critical exponents and amplitudes characterising the slow relaxation of density fluctuations in the vicinity of the transition are calculated.
Abstract: The mode-coupling theory of the liquid-glass transition is applied to the hard-sphere system. The critical exponents and amplitudes characterising the slow relaxation of density fluctuations in the vicinity of the transition are calculated. Particular attention is devoted to the description of the frozen correlations in the glass and to the critical amplitudes describing the beta -relaxation process. The latter appears to be quite local, involving only rearrangements extending over a few interatomic distances.
TL;DR: In this paper, the interplay between magnetic properties and chemical ordering in the Co1-xPtx system is investigated theoretically and experimentally and the results for the Curie temperature, magnetisation and paramagnetic susceptibility in ordered and disordered states are discussed within the framework of statistical models.
Abstract: The interplay between magnetic properties and chemical ordering in the Co1-xPtx system is investigated theoretically and experimentally. Experimental results for the Curie temperature, magnetisation and paramagnetic susceptibility in ordered and disordered states are discussed within the framework of statistical models. The authors show that the magnetic moments on Pt atoms depend sensitively on the local chemical environment. A complete equilibrium phase diagram is also calculated and compared with the experimental data.