Unusual electronic ground state of a prototype cuprate: Band splitting of single -plane _x

¹ Humboldt-Universität Berlin, Institut für Physik Invalidenstr. 110, 10115 Berlin, Germany
² Synchrotron Radiation Center - 3731 Schneider Dr., 53589 Stoughton WI, USA

Received: 25 February 2002
Accepted: 5 September 2002

Abstract

The momentum dependence of the split band of (Manzke R. et al. , Phys. Rev. B, 63 (2001) R100504) is investigated by angle-resolved photoemission spectroscopy with very high resolution along the ΓM-line. The splitting is only observable in this direction and at certain experimental conditions with respect to temperature and doping of the sample and polarization of the impinging radiation. Since bilayer effects cannot be present in this single-layer material and other sources producing a splitting are also less plausible, the results point to an unusual ground state of this system. It is discussed whether microscopic phase separation including striped phase formation, critical fluctuations coupled to electrons (hot spots) or spin charge separation within the Luttinger-liquid picture, leading to the appearance of spinon and holon excitations, is capable to describe the observations qualitatively.