Influence of magnetic imperfections on the low-temperature properties of d-wave superconductors

Abstract

We consider the influence of planar ‘‘magnetic’’ imperfections which destroy the local magnetic order, such as Zn impurities or Cu2+ vacancies, on the low-temperature properties of the cuprate superconductors. In the unitary limit, at low temperatures, for a dx2−y2 pairing state such imperfections produce low-energy quasiparticles with an anistropic spectrum in the vicinity of the nodes. We find that for the La2−xSrxCuO4 system, one is in the quasi-one-dimensional regime of quasiparticle scattering, discussed recently by Altshuler, Balatsky, and Rosengren, for impurity concentrations in excess of ∼0.16% whereas Ya-Ba-Cu-O7 appears likely to be in the true two-dimensional scattering regime for Zn concentrations less than 1.6%. We show the neutron-scattering results of Mason et al. [Phys. Rev. Lett. 71, 919 (1993)] on La1.85Sr0.14CuO4 provide strong evidence for ‘‘dirty d-wave’’ superconductivity in their samples. We obtain simple expressions for the dynamic spin susceptibility and Cu63 spin-lattice relaxation time, 63T1, in the superconducting state.

Source-reported materials — not catalogue approval

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