Oscillations of the magnetic polarization in a Kondo impurity at finite magnetic fields

The electronic properties of a Kondo impurity are investigated in a magnetic field using linear response theory. The distribution of electrical charge and magnetic polarization are calculated in real space. The (small) magnetic field does not change the charge distribution. However, it unmasks the Kondo cloud. The (equal) weight of the d-electron components with their magnetic moment up and down is shifted and the compensating s-electron clouds don't cancel any longer (a requirement for an experimental detection of the Kondo cloud). In addition to the net magnetic polarization of the conduction electrons an oscillating magnetic polarization with a period of half the Fermi wave length is observed. However, this oscillating magnetic polarization does not show the long range behavior of Rudermann-Kittel-Kasuya-Yosida oscillations because the oscillations don't extend beyond the Kondo radius. They represent an internal electronic structure of the Kondo impurity in a magnetic field. PACS: 75.20.Hr, 71.23.An, 71.27.+

Spin thermopower in interacting Rashba dots

Spintronics or spin electronics has been an active area of research based on the active control and manipulation of spin degrees of freedom. In this work we study the thermoelectric properties of a Rashba dot using the Anderson model in presence of the repulsive Coulomb interaction within the mean-field formalism. The temperature difference applied across the dot drives a spin current which depends on the Rashba coupling and chemical potential. We demonstrate that the Rashba dot in presence of the Coulomb interaction behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the impurity energy level, temperature and also the Rashba term have been observed

ESR of a magnetic impurity in a host with interconfiguration fluctuations

The electron spin resonance of a magnetic probe is considered in the interconfiguration-fluctuation host (ICF). The spin relaxation rate of a well-defined magnetic probe in the presence of the Coulomb interaction although satisfies the Korringa relation at low temperatures presents a minimum with a rise in temperature. The transition from the magnetic state to the non-magnetic state is also characterized by a minimum in the relaxation rate. The low temperature behavior of the relaxation rate with the distance between the magnetic probe and ICF ions is substantially lower than that of a pure metal

Tunneling in mesoscopic junctions using the numerical renormalization group method

We have applied the Numerical Renormalization Group method to study a mesoscopic system consisting of two samples of a metal separated by an insulating barrier with nanometer dimensions. It allows the tunnelling of a single electron from one side to the other side of the junction. The junction is represented by a generalized orthodox model, which considers the electronic scattering interaction due to the hole and the tunnelling electrons, localized in the source and in the drain electrode, respectively. We have calculated the static properties (charge transfer, charge average, quadractic charge average and specific heat) and the electric conductivity of the junction for the model parameters given by the tunneling matrix element t, the barrier energy $U=e^{2}/2C$ (where C is the capacitance of the system) and by the electronic scattering potentials $V_{L(R)}$ acting on the electrons of the left(right) electrode