Disorder effects on c-axis coupling in underdoped BSCCO

Kees van der Beek , Panayotis Spathis, Sylvain Colson, Marcin Konczykowski
Laboratoire des Solides Irradies, Ecole Polytechnique, F 91128 Palaiseau cedex, France

Marat Gaifullin,Yuji Matsuda
Institute of Solid State Physics (ISSP),The University of Tokyo, Chiba, Japan

Piotr Gierlowski
Institute of Physics of the Polish Academy of Sciences (IFPAN), Warsaw, Poland

Ming Li, Peter Kes
Kamerlingh Onnes Laboratorium, Leiden University, Leiden, the Netherlands

We study the effect of poitn defects, created by 2.5 MeV electron irradiation on the c-axis penetration depth, lc , in single crystalline Bi2Sr2CaCu2O8+d. The most important effect is the decrease of the c-axis critical current, Jcc, proportionnal to the Tc suppression. We interpret this as a n in-plane pair breaking effect. c-axis transport in the superconducting state is thought to occur through incoherent tunnelling with angular dependent transfer matrix. While the results are in quantitative agreement with the impurity assisted hopping model (IAH), the temperature dependence of lc seems to indicate an important rome of quantum fluctuations of the superconducting order parameter phase in the layers. A combined role of IAH and quantum fluctuations may also explain the effet of amorphous columnar defects on created by heavy ion irradiation on zero field c-axis properties.