Itinerant magnetism in metallic CuFe2Ge2

Theoretical calculations are performed to understand the electronic structure and magnetic properties of CuFe$_2$Ge$_2$. The band structure reveal large electron density $N(E_F)$ at the Fermi level suggesting strong itinerant character of magnetism. The Fermi surface is dominated by two dimensional sheet like structures, with potentially strong nesting between them. The magnetic ground state appears to be ferromagnetic along $a$ and antiferromagnetic in other directions. The results show that CuFe$_2$Ge$_2$ is an antiferromagnetic metal, with similarities to the Fe-based superconductors; such as magnetism with substantial itinerant character and coupling between magnetic order and electrons at the Fermi energy.Comment: 5 pages, 6 figure

Tables of X-coefficients and Lambda-factors for Triple Angular Correlation Analysis

Tables of x-coefficients and lambda-factors for triple angular correlation measurements in nuclear reaction studie

Spin waves in the (0,pi) and (0,pi,pi) ordered SDW states of the t-t' Hubbard model: Application to doped iron pnictides

Spin waves in (0,pi) and (0,pi,pi) ordered spin-density-wave (SDW) states of the t-t' Hubbard model are investigated at finite doping. In the presence of small t', these composite ferro-antiferromagnetic (F-AF) states are found to be strongly stabilized at finite hole doping due to enhanced carrier-induced ferromagnetic spin couplings as in metallic ferromagnets. Anisotropic spin-wave velocities, spin-wave energy scale of around 200meV, reduced magnetic moment, and rapid suppression of magnetic order with electron doping x (corresponding to F substitution of O atoms in La O_{1-x} F_x Fe As or Ni substitution of Fe atoms in Ba Fe_{2-x} Ni_x As_2) obtained in this model are in agreement with observed magnetic properties of doped iron pnictides.Comment: 13 pages, 3 figure

Electronic Structure and Thermoelectric Prospects of Phosphide Skutterudites

The prospects for high thermoelectric performance in phosphide skutterudites are investigated based on first principles calculations. We find that stoichiometric CoP_3 differs from the corresponding arsenide and antimonide in that it is metallic. As such the band structure must be modified if high thermopowers are to be achieved. In analogy to the antimonides it is expected that this may be done by filling with La. Calculations for LaFe_4P_12 show that a gap can in fact be opened by La filling, but that the valence band is too light to yield reasonable p-type thermopowers at appropriate carrier densities; n-type La filled material may be more favorable.Comment: 3 pages, 3 figures, 1 tabl

Cohesion of BaReH9_9 and BaMnH9_9: Density Functional Calculations and Prediction of (MnH9)2−_9)^{2-} Salts

Density functional calculations are used to calculate the structural and electronic properties of BaReH$_9$ and to analyze the bonding in this compound. The high coordination in BaReH$_9$ is due to bonding between Re 5$d$ states and states of $d$-like symmetry formed from combinations of H $s$ orbitals in the H$_9$ cage. This explains the structure of the material, its short bond lengths and other physical properties, such as the high band gap. We compare with results for hypothetical BaMnH$_9$, which we find to have similar bonding and cohesion to the Re compound. This suggests that it may be possible to synthesize (MnH$_9)^{2-}$ salts. Depending on the particular cation, such salts may have exceptionally high hydrogen contents, in excess of 10 weight

Neutrino Induced Charged Current 1π+\pi^+ Production At Intermediate Energies

The charged current one pion production induced by $\nu_\mu$ from nucleons and nuclei like $^{12}$C and $^{16}$O nuclei has been studied. The calculations have been done for the incoherent and the coherent processes from nuclear targets assuming the $\Delta$ dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon and renormalization of $\Delta$ properties in a nuclear medium. The effect of final state interactions of pions has been taken into account. The theoretical uncertainty in the total cross sections due to various parameterizations of the weak transition form factors used in literature has been studied. The numerical results for the total cross sections are compared with the recent preliminary results from the MiniBooNE collaboration on $^{12}$C and could be useful in analyzing future data from the K2K collaboration.Comment: 10 pages, 6 figures, 1 tabl