Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 29: Superconductivity - Mechanisms, Phase Diagram, Competing Order

TT 29.7: Vortrag

Donnerstag, 29. März 2007, 17:30–17:45, H18

^63,65Cu Nuclear Quadrupole Resonance Study of Impurity doped NdBa₂(Cu,Ni,Zn)₃O_6+y — •Hans-Joachim Grafe¹, Franziska Hammerath¹, Anastasia Vyalikh¹, Grzegorz Urbanik¹, Vladislav Kataev¹, Thomas Wolf², and Bernd Büchner¹ — ¹IFW Dresden, Institut für Festkörperforschung, Postfach 270116, 01171 Dresden, Germany — ²Forschungszentrum Karlsruhe, IFP, D-76021 Karlsruhe, Germany

We present ^63,65Cu Nuclear Quadrupole Resonance (NQR) measurements on slightly underdoped NdBa₂(Cu,Ni,Zn)₃O_6+y single crystals with 11.5 % magnetic (Ni) and 12 % non-magnetic (Zn) impurities. Superconductivity is completely suppressed in both samples. By fitting the spectra we can estimate the impurity content of the chains and the planes. At low temperatures the Ni induces a wipeout of the Cu NQR signal intensity comparable to that found in stripe ordered lanthanum cuprates. In contrast, the intensity of the Zn doped sample is not changed down to the lowest temperatures, and the spin lattice relaxation rate is suppressed. This difference enlightens the different effect of nonmagnetic (S = 0) and magnetic (S = 1) impurities on the spin dynamics in the CuO₂ planes, and directly confirms current theoretical positions on this topic.