Nodes of the superconducting gap probed by electronic Raman scattering in HgBa₂CaCu₂O_6+δ single crystals

¹ Physique de la Matière Condensée, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
² Physique Statistique, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
³ Physique de l'Etat Condensé, DRECAM/SPEC, CEA Saclay, 91191 Gif-sur-Yvette, France

Received: 28 April 1997
Accepted: 13 June 1997

Abstract

Pure electronic Raman spectra with no phonon structures superimposed to the electronic continuum are reported, in optimally doped single crystals K). As a consequence, the spectra in the and symmetries, including the crucial low-energy frequency dependence of the electronic scattering, are directly and reliably measured. The and, most strikingly, the spectra exhibit a strong intrinsic linear term, which suggests that the nodes are shifted from the [110] and [ 10] directions, a result inconsistent with a pure model.