FIZIKA A 8 (1999) 3 , 107-112

LETTER TO THE EDITOR

DEFECT-INDUCED CHANGES IN THE SPECTRAL PROPERTIES OF HIGH-T_c CUPRATES

I. VOBORNIK^a , H. BERGER^a, F. RULLIER-ALBENQUE^b, G. MARGARITONDO^a, D. PAVUNA^a, L. FORRO^c and M. GRIONI^a

^aInstitut de Physique Appliquée, Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland

^bLaboratoire des Solides Irradiés, CEA, Ecole Polytechnique, 91128 Palaiseau Cedex, France

^cLaboratoire de Physique des Solides Semicristallins, IGA, Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland

Dedicated to Professor Boran Leontić on the occasion of his 70^th birthday

Received 9 November 1999; revised manuscript received 1 February 2000
Accepted 14 February 2000

Superconductivity in high-T_c cuprates is particularly sensitive to disorder due to the unconventional d-wave pairing symmetry. We investigated effects of disorder on the spectral properties of Bi₂Sr₂CaCu₂O_8+x high-T_c superconductor. We found that already small defect densities suppress the characteristic spectral signature of the superconducting state. The spectral line shape clearly reflects new excitations within the gap, as expected for defect-induced pair breaking. At the lowest defect concentrations the normal state remains unaffected, while increased disorder leads to suppression of the normal quasiparticle peaks.

PACS numbers: 74.25.-q, 74.62.Dh, 74.72.Hs
UDC 538.945

Keywords: superconductivity, high-T_c cuprates, effects of disorder, spectral properties, Bi₂Sr₂CaCu₂O_8+x, defect-induced pair breaking, suppression of the normal quasiparticle peaks

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