Effects of magnetic impurity Co on stripe phase of (Bi/Tl) $_\mathsf2$(Sr/Ba)$_\mathsf2$CaCu$_\mathsf2$O $_\mathsf{8+\delta}$ superconductors

Abstract.

The effects of Co impurity substitution at the Cu site of bilayer bismuth and thallium cuprates have been studied over a wide range of carrier concentration. For both the systems it is found that the suppression of the superconducting transition temperature, T _c is more rapid in the underdoped region. No anomalous suppression of T _c at p $\sim$ 1/8 (p is the hole concentration per Cu ion) is found for different Co concentrations. This indicates that magnetic impurity Co behaves differently with respect to pinning of dynamical stripes as was observed in the case of non-magnetic impurity Zn by Akoshima et al. [Phys. Rev. B 57, 7491 (1998)] in bilayer bismuth cuprate. Pseudogap magnitude (E _g ) for each Co doping are observed to have a correspondence with a related characteristic temperature T ^* obtained from thermopower measurements where T ^* increases with increasing Co-concentration at a fixed carrier concentration. Both T ^* and E _g are found to follow an inverse power law ($\sim$ $\frac{1}{p^n}$) with different n values.