Evidence of coexistence of Co3+ with Co2+ in ceramic Co3TeO6 through XANES, DC magnetization and first principal studies is provided. XANES along with linear combination fit provide relative concentrations of Co2+ and Co3+.Temperature dependent DC ma
gnetization exhibits the same antiferromagnetic behavior as observed in single crystal. The presence of both Co2+ and Co3+ suggests that if the later is in high spin state, the effective magnetic moment is similar to that observed in single crystal studies. In contrast, if Co3+ is in low spin state effective magnetic moment is similar to that observed in Co3O4. It is further shown that both Co2+ and Co3+ in high spin states constitute a favorable ground state through first principle calculations where Rietveld refined Synchrotron X-ray diffraction data are inputs.
Andreev interferometers, normal metal wires coupled to superconducting loops, display phase coherent changes as the magnetic flux through the superconducting loops is altered. Properties such as the electronic and thermal conductance of these devices
have been shown to oscillate symmetrically about zero with a period equal to one superconducting flux quantum, $Phi_o = h/2e$. However, the thermopower of these devices can oscillate symmetrically or antisymmetrically depending on the geometry of the sample, a phenomenon not well understood theoretically. Here we report on thermopower measurements of a double-loop Andreev interferometer where two Josephson currents in the normal metal wire may be controlled independently. The amplitude and symmetries of the observed thermopower oscillations may help to illuminate the unexplained dependence of oscillation symmetry on sample geometry.
