High-field magnetization of giant moment-spin glass PdMn alloys in pulsed fields up to 40 T

Magnetization curves up to 40 T are presented for $\text{Pd}$Mn alloys with Mn concentrations between 0.48 and 9.8 at.%. Estimates for the exchange parameters and saturation moments are obtained, and a comparison with Monte Carlo simulations is made.     

The frequency dependence of the ac susceptibility of the PdMn spin glass

We have measured the frequency dependence of the ac susceptibility _X(T) for three alloys of $\text{Pd}$Mn in the spin-glass regime. A strong dependence of _X(T) on frequency is observed near and below the freezing temperature in contrast to the archetypal $\text{Cu}$Mn spin glass. We discuss possible reasons for these differences.     

Anomalous lattice parameters and hydrogen solubilities in dilute PdFe alloys

Lattice parameters for fcc $\text{Pd}$Fe alloys exhibit a maximum at X_Fe = 0.003 where X_Fe is the atom fraction Fe. In this region of alloy composition the solubility of H₂ is also a maximum. It is suggested that the “giant moments” found in this region cause the anomalous lattice expansion which in turn is the major source of the enhanced H₂ solubility.     

Superconducting properties of ZnCr and ZnMn alloys

Measurements on the superconducting critical temperature T_c and critical field, H_c, of $\text{Zn}$Cr and $\text{Zn}$Mn alloys, down to 0.037°K are presented.The variation of T_c with increasing concentration depends strongly on T_cp/θ, with θ a characteristic temperature, while effects of H_c are similar to previously studied alloys.     

The impurity resistivity and resistivity minima in AlCr and AlMn alloys

The impurity resistivity of $\text{Al}$Cr between 1.5 and 50°K was determined with a characteristic temperature for the T² variation θ₁=960±40°K. The behaviour of the resistivity minimum both in $\text{Al}$Cr and $\text{Al}$Mn alloys with impurity concentration provides evidence that a T³ phonon resistivity is found also in aluminium with anomalous impurity resistivity.     

Resistivity of dilute AlMg and AlMn between 0° and 100°C a generalized approach

We have measured the resistivity of $\text{Al}$Mg and $\text{Al}$Mn up to 0.5 at. % impurity concentration between 0° and 100°C. The results for the resistivity for both systems can be analysed within one generalized model in which spinfluctuations as well as changes in the electron-phonon interaction are considered. For $\text{Al}$Mn a calculation of the impurity contribution to d?/dT is attempted. For $\text{Al}$Mg there are indications that the superconducting T_c will increase with Mg concentration.     

Study of the local susceptibility in the Fe: Au system

Mössbauer effect measurements of the Fe: $\text{Au}$ system are reported which yield the local susceptibility of the Fe ions. At high temperatures (T ? 10°K) a Curie Weiss law with θ₁ = 9.8°K is observed, whereas at low temperatures the Curie Weiss temperature is θ₂ = 0.45°K. In both temperature regimes the local susceptibility is a linear function of the total susceptibility. In addition below 4°K the local magnetization is a linear function of the total magnetization up to external fields of 60 kG.     

Experimental susceptibility of CuFe, AgFe and MoFe and the results of the Wilson theory

The low temperature susceptibility of the local moment system $\text{Mo}$Fe has been measured by the Mössbauer effect. The susceptibility for this system and for the system $\text{Cu}$Fe, $\text{Ag}$Fe and $\text{Au}$Fe show general agreement with the prediction of the Wilson theory.     

Deviation from Matthiessen rule in Mg-Cd and Cd-Mg

The interference term between electron-phonon and electron impurity scattering has been evaluated for $\text{Mg}$Cd and $\text{Cd}$Mg and found to be negative, in agreement with experiment. It is shown that measurements on single crystal should give valuable information.     

Isospin bounds for energy partition in ee and NN annihilation

In reactions such as $\text{e}$e → anything, $\text{N}$N → anything, the final state (neglecting secondary isospin violating decays) is customarily supposed to have isospin zero or one. We show that for such states the average fraction (X) of the energy carried away by neutral pions is bounded by $\text{X<}\text{(9+√41)}\text{20}\text{≈0.77}$, when I₃ = 0 (e.g., for ee, pp, nn) and by $\text{X>}\text{(11?√41)}\text{40}\text{≈0.115}$, when I₃=±1 (e.g., for pn or np).     

Spin-glass transition revisited from a partial derivative of specific heat in CuMn 0.25 at%

From general thermodynamical relations we derive the magnetic field expansion of the specific heat for the paramagnetic phase of a spin glass. Experimental results for the magnetocaloric effect of a $\text{Cu}$Mn 0.25 at% allow us to determine the successive terms of this expansion. We reach a precision of several percent for the terms which are as small as 10^-3 or 10^-4 of the total specific heat.     

Magnetostriction of dilute AuYb and AuTb monocrystals

We have made magnetostriction measurements on dilute $\text{Au}$Yb and $\text{Au}$Tb monocrystals at low temperatures. The shape magnetostriction follows the sign of the quadrupolar Stevens factor α_J of the earth but, in contrast to our recent results on silver-rare earth dilute alloys, the 〈001〉 and 〈111〉 effects have opposite signs. We obtain very good agreement between experiment and calculations based on the known cubic crystal-field parameters and we estimate the ion-lattice coupling parameters. The volume magnetostriction is positive, but very small, about two orders of magnitude smaller than the shape effect.     

The electronic structures of cis-polyacetylene

The electronic structures of two possible forms of the so-called $\text{cis}$-skeletal polyacetylene ($\text{cis}$-polyacetylene) are investigated on the basis of the tight-binding LCAO-SCF-MO method under the CNDO/2 version. The analyses of the total energies per unit cell, the π bond orders and the interatomic interaction energies as to the both forms predict the $\text{cis}$-transoid backbone for the $\text{cis}$-polyacetylene. The examination of the patterns of particular molecular orbitals of the hypothetical $\text{cis}$-polymer with equal C-C bond lengths also supports the $\text{cis}$-transoid form.     

Pseudoscalar mesons in the c-c and b-b systems

It is shown that the pseudoscalar η_c and “η_c” (η_b and “η_b”) with M ≈ 2.80 and 3.51 GeV (9.17 and 9.88 GeV) can be predicted by using the radial mixing model, where the “η_c” and “η_b” are the excited 0^- states in the $\text{c-}\text{c}$ and $\text{b-}\text{b}$ systems, respectively, and the former would correspond to the observed 0^- meson with M ≈ 3.45 GeV in charmonium.     

Thermopower of concentrated AuCr alloys

Measurements are presented of the thermopower of three concentrated $\text{Au}$Cr (0.9, 4.9 and 10.6 at.%Cr) alloys between 4 and 500°K. Considerable differences are observed in the thermopower compared with $\text{Au}$Fe alloys in a similar concentration range. Possible reasons for these differences are discussed in terms of current ideas on spin glasses and the pair model of Matho and Béal-Monod.     

Evidence for high mass NN and NNπ enhancements observed in pd interactions at 5.55 GeV/c

Based on 4085 $\text{p}\text{n→Xπ}{}^{\mathrm{?}}$ events, X denoting a neutral $\text{N}$N or $\text{N}\text{Nπ}$ system, we present evidence for 5.1 and 3.1 standard deviation enhancements at the X mass of 2.85 and 3.05 GeV/c², respectively. The lower mass bump has a width of Λ ? 39 GeV/c² while the 3.05 GeV/c² is seen as a one bin accumulation (20 GeV/c² width). The relevance of these peaks is discussed.     

Optical model analysis of p-atoms

We examine how different types of form factors for $\text{p}$-nucleus optical potential affect the analysis of X-ray data in $\text{p}$-atoms. We also study the effect of L·S force due to strong interaction in $\text{p}$-atoms.     

Electronic structure of the GeGaAs (111) and (111) heterojunctions

The electronic density of states for GeGaAs (111) and ($\text{1}$$\text{1}$$\text{1}$) heterojunctions has been calculated. No interface states in the fundamental gap are found. A sizeable density of interface states below the top of the valence band is found for GeGa bonds-(111) junctions-interface states in the ionic gap are reported. The effect of varying the amount of the valence band discontinuity across the interface is discussed.     

Comparison of pp and pp interactions at s = 53 GeV

Results are presented from the first p$\text{p}$ colliding beam runs at the CERN ISR, using the UA5 streamer chamber detector. p$\text{p}$ interactions at $\text{s}\text{= 53}\text{GeV}$ are compared with pp data taken in the same experiment. The results are in good agreement with extrapolations of low-energy p$\text{p}$ data.     

Mössbauer effect measurements on a AuFe spin glass

Zero field Mössbauer measurements have been carried out between 1.9 and 30 K and at room temperature on a $\text{Au}$-3 at% Fe sample. There is a quite well defined change of regime at about 19.5 K, well above the cusp temperature of this sample which was measured to be 16.4 K. In the temperature region below 19.5 K the spectra can best be described in terms of a static, inhomogeneously broadened field distribution, and at higher temperatures the spectra are compatible with relaxation broadening. Estimated relaxation rates in this regime are similar to those obtained by other techniques.