Spin and Charge Josephson effects between non-uniform superconductors with coexisting helimagnetic order

We consider the spin and charge Josephson current between two non-uniform Fulde-Ferrel-Larkin-Ovchinnikov superconductors with helimagnetic order. We demonstrate that the presence of the helimagnetic phase generates a spin Josephson effect and leads to additional contributions to both single-particle and Josephson charge current. It is shown that for such systems the AC effect differs more radically from the DC effect than in the case of a BCS superconductor with helimagnetic order considered earlier in the literature [M. L. Kuli\'c and I. M. Kuli\'c, Phys. Rev. B {\bf 63}, 104503 (2001)] where a spin Josephson current has also been found. In our system the most interesting effect occurs in the presence of an external magnetic field and in absence of voltage, where we show that the charge Josephson current can be tuned to zero while the spin Josephson current is non-vanishing. This provides a well controlled mechanism to generate a spin supercurrent in absence of charge currents.Comment: final versio

Ionization potentials and charge localization in small charged group 12 clusters

For small size, the cluster Xn with X = Hg, Cd or Zn displays a van der Waals bond. A model Hamiltonian has been proposed for the singly (doubly) ionized van der Waals clusters ${\mathrm{X}}_n^{+}$ (${\mathrm{X}}_n^{++}$). The first and second ionization potentials of Xn have been calculated. A good agreement is obtained with the available experiment values of the first ionization potential of mercury and cadmium. The stability and the metastability of ${\mathrm{X}}_n^{++}$ are discussed. The energy curves versus the bond length for ${\mathrm{Hg}}_2^{++}$, ${\mathrm{Cd}}_2^{++}$ and ${\mathrm{Zn}}_2^{++}$ have been determined. The hole(s) in charged clusters ${\mathrm{X}}_n^{+}$ and ${\mathrm{X}}_n^{++}$ for 2 ≤ n ≤ 7 is (are) mainly delocalized, except for ${\mathrm{Hg}}_n^{+}$ with n ≥ 4 where the hole is localized on two or three sites

Determination of some C60 electronic properties. Application to the cohesive energy in C60 ionic compounds

The electron affinities E An, defined as the gained energy in C60 + ne → Cn- 60 reactions, are determined by the Gutzwiller method for free C 60. We use them in the study of the cohesive energy of C60M x compounds, where M = K, Rb and x = 3 or 6. We consider 4 terms: the Madelung, ionization, core-repulsion and crystal field energies. The core-repulsion parameters are taken from the literature for C60 K3 and determined for the other compounds. We show that the cohesive energy of the considered compounds is positive only if we take into account the crystal field term. The stability of other C60 ionic compounds is discussed.Les affinités électroniques E An des agrégats libres C60, définies comme l'énergie gagnée dans la réaction C 60 + ne → Cn-60, sont déterminées par la méthode de Gutzwiller. Nous les utilisons dans l'étude de l'énergie de cohésion de composés C60Mx, avec M = K, Rb et x = 3 ou 6. Nous considérons 4 termes : les énergies de Madelung, d'ionisation, de répulsion de coeur et de champ cristallin. Les paramètres décrivant la répulsion de coeur sont tirés de la littérature pour C60 K3 et sont déterminés pour les autres composés. Nous montrons que l'énergie de cohésion des composés considérés n'est positive que si l'on tient compte du terme de champ cristallin. La stabilité d'autres composés ioniques du C60 est aussi discutée