[en] The intermediate valence compounds Yb₂M₃Ga₉ (M = Rh, Ir) exhibit an anisotropic magnetic susceptibility. We report measurements of the temperature dependence of the 4f occupation number, n_f(T), for Yb₂M₃Ga₉ as well as the magnetic inelastic neutron scattering spectrum S_mag(ΔE) at 12 and 300 K for Yb₂Rh₃Ga₉. Both n_f(T) and S_mag(ΔE) were calculated for the Anderson impurity model with crystal field terms within an approach based on the non-crossing approximation. These results corroborate the importance of crystal field effects in these materials; they also suggest that Anderson lattice effects are important to the physics of Yb₂M₃Ga₉

[en] We derive the extension of the Hubbard model to include Rashba spin-orbit coupling that correctly describes Aharonov-Bohm and Aharonov-Casher phases in a ring under applied magnetic and electric fields. When the ring is connected to conducting leads, we develop a formalism that is able to describe both, Kondo and interference effects. We find that in the Kondo regime, the spin-orbit coupling reduces strongly the conductance from the unitary limit. This effect in combination with the magnetic flux, can be used to produce spin polarized carriers.

[en] We present an eigenvalue theory to study the stochastic dynamics of nonstationary time-periodic Markov processes. The analysis is carried out by solving an integral operator of the Fredholm type, i.e. considering complex-valued functions fulfilling the Kolmogorov compatibility condition. We show that the asymptotic behavior of the stochastic process is characterized by the smaller time-scale associated to the spectrum of the Kolmogorov operator. The presence of time-periodic elements in the evolution equation for the semigroup is considered to apply a Floquet analysis, then the first non-trivial Kolmogorov's eigenvalue is interpreted from a physical point of view. This nontrivial characteristic time- scale strongly depends on the interplay between the stochastic behavior of the process and the time-periodic structure of the Fokker-Planck equation for continuous processes, or the periodically modulated Master Equation for discrete Markov processes. We present pedagogical examples in a finite dimensional vector space to calculate the Kolmogorov characteristic time-scale for discrete Markov processes. (author)

[en] We report measurements of the inelastic neutron scattering spectrum for the anisotropic intermediate valence system Yb₂Rh₃Ga₉. Calculations for the Anderson impurity model with crystal field terms within an approach based on the non-crossing approximation have been performed for the inelastic neutron scattering spectrum as well as other thermodynamic quantities. These results corroborate the importance of crystal field effects in these materials. They also suggest that Anderson lattice effects are important to the physics of Yb₂Rh₃Ga₉