The magnetic susceptibilities of NO and OH

A non-isothermal kinetic equation for the distribution function of a sub-system weakly coupled to a bath is derived by modification of the analysis and assumptions of a previous paper [1]. The equation has the form of a generalized non-isothermal Fokker-Planck equation when it is linearized in thermodynamic gradients and only terms through second order in the coupling parameters are retained. Higher order terms in the coupling parameter do not diverge with time. The equation is compared with certain ‘exact’ model results of Ullersma and with the coherence time method. The equation is used to calculate a jump rate for diffusion of a harmonic particle weakly coupled to a lattice and it is found that the jump rate becomes independent of the mass of the particle for a heavy enough particle. The source of the discrepancy of this result with a similar calculation of Prigogine and Bak is indicated. The model of the jump rate is inappropriate for diffusion in a thermal gradient and more appropriate models of the jump are briefly considered. A brief comparison of the derivation of the kinetic equation with the Fano coherence time approximation is made and a difference is noted.     

Coupled-Hartree-Fock calculations of susceptibilities and magnetic shielding constants

Coupled Hartree-Fock calculations on the susceptibilities X and magnetic shielding constants σ are reported for the title molecules. Very large gaussian basis sets have been used in order to come sufficiently close to the Hartree-Fock limit. The basis set dependence of X and σ is discussed. In addition the applicability of two methods (maximum of X [20] and closure relations [21, 22]) for the prediction of the best gauge origins is investigated.

For C₂H₂, C₂H₄ aand C₂H₆ accurate theoretical results for the complete tensors of X and σ are given for the first time. For ethylene antishielding of σ _yy ^C is observed and illustrated by means of the induced electric currents.     

Initial magnetic susceptibilities of iron and nickel aerosol powders

The dependence on angle is considered for the hysteresis-free initial susceptibilities _a and _ar together with the initial susceptibility _o for iron and nickel aerosol powders, as well as the effects on these characteristics from changes in powder packing density. Estimates are made of the negative-interaction fields, and a quantitative comparison is made between the observed _ar() and theoretical values by means of the pair model. The correlation between the experimental and theoretical relationships confirms the concepts used on the predominant effects from magnetostatic interaction in the mechanism for magnetization reversal in powders of materials with low anisotropy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, pp. 40–43, July, 1984.     

Intrinsic and extrinsic magnetic susceptibilities of some TCNQ complexes

The magnetic susceptibilities (χ) of quinolinium·(TCNQ)₂, N-methyl phenazinium·TCNQ and Li·TCNQ were measured from 2 to 300 K and are discussed in connection with the low-temperature specific heats (C) measured by other authors, χ is decomposed into three parts: χ_d the temperature-independent part, χ_c, Curie-Weiss type paramagnetism, and χ_p, the remainder. Correspondingly, C is composed of three terms, γT, H/T² and αT³. The electronic state of these substances is discussed in terms of each type of susceptibility.The model, on which the above separation of χ and C is based, defines two types of electrons: localized electrons associated with a magnetic moment and band electrons. Though this model is useful phenomenologically, it is shown that the analysis of χ on the basis of this model indicates less band electrons and more localized electrons or stronger magnetic interactions than does that of C.     

Optical and magnetic susceptibilities for semiconductors and alkali halides

Optical susceptibility, electronic polarizability and magnetic susceptibility values have been evaluated from optical electronegativities. The validity of the proposed empirical relations has been tested in the case of II–VI, III–V group semiconductors and alkali halides. The estimated values of these parameters are in good agreement with the available experimental data. There has been no report on the direct estimation of optical susceptibility and magnetic susceptibility using the concept of optical electronegativity.     

Interplay of magnetic and superconducting proximity effects in ferromagnet-superconductor-ferromagnet trilayers

We present theoretical results on the interplay of magnetic and superconducting orders in diffusive ferromagnet-superconductor-ferromagnet trilayers. The induced triplet superconducting correlations throughout the trilayer lead to an induced spin magnetization. We include self-consistency of the order parameter in the superconducting layer at arbitrary temperatures, arbitrary interface transparency, and any relative orientation of the exchange fields in the two ferromagnets. We propose to use the torque on the trilayer in an external magnetic field as a probe of the presence of triplet correlations in the superconducting phase.     

Magnetic structures and magnetic susceptibilities of terbium oxysulfide and oxyselenide

For the two isomorphous compounds Tb₂O₂S and Tb₂O₂Se, the magnetic susceptibility measurements on powder samples show an antiferromagnetic ordering with Néel temperatures of about 7.7 and 7K respectively. Differing in this respect from the other rare earth oxyselenides, the magnetic anisotropy of Tb₂O₂Se at low temperature is weaker than that of Tb₂O₂S.We also determine the magnetic structures of these two compounds by neutron diffraction experiments at 1.5K. The magnetic cell is orthohexagonal and doubled along the c-axis; the magnetic moments make an angle, with the c-axis, of 47 ± 10° for Tb₂O₂S and 30 ± 10° for Tb₂O₂Se and the moment values at 1.5K are 8.14 ± 0.2μ_B and 6.5 ± 0.2μ_B, respectively.It is rather exceptional that in a rare earth uniaxial compound the magnetic moment makes an angle with the c-axis. However we interpret this situation by the fact that several levels exist very near to the ground state. The crystal field calculations are in good agreement with the experimental results.     

Anomalous magnetic susceptibilities of the alkaline earth hexammines

The magnetic susceptibility of the metallic compounds Ca(NH₃)₆, Sr(NH₃)₆ and Ba(NH₃)₆ has been measured by the Faraday method in the range 2–200 K. The susceptibility of Ca(NH₃)₆ is strongly dependent on temperature and exhibits a broad minimum near 120 K and a peak near 10 K. In contrast to Ca(NH₃)₆, the susceptibilities of Sr(NH₃)₆ and Ba(NH₃)₆ are diamagnetic and decrease rapidly as the temperature is lowered. At low temperatures Ba(NH₃)₆ has the largest mass susceptibility of any nonsuperconducting metal.     

Linear and nonlinear AC magnetic susceptibilities in intercalation compound FexTiS2

The harmonic, second and third higher harmonic components of the induced voltage of a sample coil under application of a low-field ac magnetic field, with and without static field, have been measured in the spin-glass, cluster-glass, and ferromagnetic phases of the intercalation compound Fe_xTiS₂ over the temperature range 1.5-300 K. Using a phenomenological expression for the magnetization, we have obtained independently the relative magnitudes of the linear and nonlinear ac magnetic susceptibilities χ₀, χ₁ and χ₂ for each magnetic phase.     

Interplay between the magnetic fluctuations and superconductivity in lanthanum cuprates

We report an analysis of the magnetic fluctuations in superconducting La_2?xSr_xCuO₄ and related lanthanum cuprates that have different symmetry of the low-temperature structure. NMR and ESR investigations revealed a dynamical coexistence of superconductivity and the antiferromagnetic correlations in most of the superconductivity region of the phase diagram. We show that, for all compounds, regardless of their low-temperature symmetry and their superconducting properties, the enhancement of the spin stiffness near 1/8 doping takes place.     

Interplay of iron and rare-earth magnetic order in rare-earth iron pnictide superconductors under magnetic field

The magnetic properties of iron pnictide superconductors with magnetic rare-earth ions under strong magnetic field are investigated based on the cluster self-consistent field method. Starting from an effective Heisenberg model, we present the evolution of magnetic structures on magnetic field in RFeAsO(R = Ce, Pr, Nd, Sm, Gd, and Tb) and RFe_2As_2(R =Eu) compounds. It is found that spin-flop transition occurs in both rare-earth and iron layers under magnetic field, in good agreement with the experimental results. The interplay between rare-earth and iron spins plays a key role in the magneticfield-driven magnetic phase transition, which suggests that the rare-earth layers can modulate the magnetic behaviors of iron layers. In addition, the factors that affect the critical magnetic field for spin-flop transition are also discussed.     

Interplay between chiral magnetic and Kondo effects in Weyl metal phase

We investigate the Kondo effect in a Weyl metal state, which occurs from a spin-orbit coupled Dirac metal phase under magnetic fields. We start from an effective field theory in terms of low-energy fermions on a pair of chiral Fermi surfaces, which takes into account both the Berry curvature and chiral anomaly. Resorting to the U(1) slave-boson mean-field theory, we find that the effective Kondo temperature increases monotonically as a function of the external magnetic field due to enhancement of the density of states. The enhancement is originated from the chiral magnetic effect which is novel feature of Weyl metals. This leads to the prediction of the magnetic-field dependence in the logarithmic temperature dependence of the longitudinal magnetoconductivity.     

Magnetization process and principal magnetic susceptibilities in RbMnF3

The temperature dependence of χ_⊥, initialχ_p (powder), and evaluated χ_∥ for RbMnF₃ are reported for the temperature range of 4.2–106 K. A shallow minimum at $\text{T}\text{T}{}_{\mathrm{N}}\text{? 0.72}$ is observed in χ_⊥. The field dependence of the magnetization shows a smooth rotation of the spins to a normal direction above H_c ? 2.43 kOe at 4.2 K.     

Charge susceptibilities of armchair graphene nanoribbon in the presence of magnetic field

We present the behaviors of both dynamical and static charge susceptibilities of undoped armchair graphene nanoribbon using the Green's function approach in the context of tight binding model Hamiltonian.Specifically,the effects of magnetic field on the the plasmon modes of armchair graphene nanoribbon are investigated via calculating the correlation function of charge density operators.Our results show that the increase of magnetic field makes the high-frequency plasmon mode for both metallic and insulating cases disappear.We also show that low-frequency plasmon mode for metallic nanoribbon appears due to increase of magnetic field.Furthermore,the number of collective excitation modes increases with ribbon width at zero magnetic field.Finally,the temperature dependence of the static charge structure factor of armchair graphene nanoribbon is studied.The effects of both magnetic field and ribbon width on the static charge structure factor are discussed in detail.     

Interplay of electronic,magnetic and structural properties of surface-supported clusters

We present first theoretical evidence revealing the influence of structural changes on the spin-polarized surface states of large Co nanoislands grown on Cu(111). The minority density of electronic states possesses a pronounced peak whose energetic position depends sensitively on the Co layers stacking order. Our results suggest a way to deduce the stacking order of large Co nanoislands using scanning tunnelling microscopy/spectroscopy.     

Influence of a magnetic field on susceptibilities measurements in the nematic phase

We give a simple calculation of the influence of long wavelength fluctuations on the elements of second order tensors describing the properties of nematics, submitted to the action of a magnetic field. A careful analysis of the field dependence of the measured values, should give the validity domain of the Frank elastic theory.