Dynamical magnetic susceptibility in the lamellar cobaltate superconductor NaxCoO2.yH2O

摘要: We systematically analyze the influence of superconducting gap symmetry and electronic structure on dynamical spin susceptibility in ${\mathrm{Na}}_{x}\mathrm{Co}{\mathrm{O}}_{2}\ensuremath{\cdot}y{\mathrm{H}}_{2}\mathrm{O}$ within three different models: The single ${a}_{1g}$-band model with nearest-neighbor hoppings, realistic three-band ${t}_{2g}$ with, without ${e}_{g}^{\ensuremath{'}}$ pockets present at Fermi surface. show that magnetic response normal state is dominated by incommensurate antiferromagnetic density wave fluctuations large momenta agreement experimental temperature dependence spin-lattice relaxation rate. Also, we demonstrate presence or absence surface does not significantly affect this conclusion. In our results for ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$- ${d}_{xy}$-wave symmetries order parameter are consistent data exclude nodeless ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}+i{d}_{xy}$-wave symmetry. further point out spin-resonance peak proposed earlier improbable band ${\mathrm{Na}}_{x}\mathrm{Co}{\mathrm{O}}_{2}\ensuremath{\cdot}y{\mathrm{H}}_{2}\mathrm{O}$. Moreover, even if resonance confined to vector disappears away from it.