High-field magnetization of PdMn and PdFeMn spin glass-ferromagnetic alloys

We have measured the low-temperature magnetization of $\text{Pd}$Mn (4.0 and 9.8 at% Mn) and $\text{Pd}$FeMn (0.35 at% Fe, 0.5 at% Mn) with fields ? 15T. A different magnetization behaviour is noted between the 9.8 at% spin glass and the alloys with lower Mn-concentrations. The latter show a ferromagnetic character and no irreversibilities or relaxation effects.     

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.     

Mean free path dependence of RKKY interaction in AuCuFe and AuCuMn spin glass alloys

The dependence of RKKY interaction on the mean free path of the conduction electrons in spin glass alloys has been investigated by varying the concentration of copper in gold in a binary host alloy. The experimental data are in agreement with theory.     

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.     

Spin density waves in dilute CrRu alloys

Neutron diffraction measurements were made on powder samples of Cr_{1 -x}Ru_x (x = 0.003, 0.015 and 0.050) alloys to established the types of antiferromagnetic order in this system. The results show that three types of antiferromagnetic order (longitudinal-incommensurate, transverse-incommensurate and commensurate) occur within this concentration range. The Néel temperatures for the three alloys are 380, 480 and 514 K, respectively. Only the commensurate phase develops in the 1.5 and 5.0% samples, while all three occur in the 0.3% one. Thermal expansion (determined from neutron diffraction spectra at various temperatures) as well as low-temperature susceptibility measurements show that the behaviour of the 0.3% alloy differs significantly from that of the other two. Both the susceptibility and thermal expansion present an anomaly at a temperature in agreement with the incommensurate-commensurate phase transition observed by neutron diffraction.     

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 nature of ordering in dilute Pt based alloys

Results are presented which suggest that, at low impurity concentrations (? 3 at.%), only near-neighbour impurity pairs order in $\text{Pt}$Fe and $\text{Pt}$Co.     

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.     

Vacancy-solute binding in Al-Zn alloys

A reanalysis of the resistometric data obtained by Takamura on quenched $\text{Al}$-Zn yields a vacancy-solute binding enthalpy considerably less than Takamura's estimate and more in line with the results of annealing experiments. The value obtained, 0.08 eV, is still about four times larger than estimates from positron annihilation experiments.     

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.     

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.     

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.     

Nuclear orientation experiemnts on Al2LaCe alloys

Nuclear orientation experiments on ^137mCe impurities in Al₂La show directly at almost 0 K that these alloys correspond to the magnetic conditions assumed by Müller-Hartmann and Zittartz.     

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.     

Q gravity

The geometrical structure of an extended theory of gravitation incorporating the quaternion field is investigated. A lagrangian is constructed and shown to be pure real as a consequence of the geometrical structure. The structure of spacetime becomes nonabelian; however, the base manifold in which physics takes place, remains real and n-dimensional.     

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.     

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).     

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.     

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.     

Reduction of the Kondo temperature in low temperature deposited alloy films of CuFe

The low temperature resistance anomaly has been investigated in highly disordered $\text{Cu}$Fe films (50–200 ppm) after quench condensation and after annealing of the films at different temperatures, which reduces the degree of disorder. An analysis of the data shows that with respect to the films annealed at room temperature and to bulk samples the Kondo temperature of a disordered film is reduced by a factor of two.