Peets DC, Hawthorn DG, Shen KM, Kim YJ, Ellis DS, Zhang H, Komiya S, Ando Y, Sawatzky GA, Liang R, Bonn DA, Hardy WN. X-ray absorption spectra reveal the inapplicability of the single-band Hubbard model to overdoped cuprate superconductors.
PHYSICAL REVIEW LETTERS 2009;
103:087402. [PMID:
19792760 DOI:
10.1103/physrevlett.103.087402]
[Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2009] [Indexed: 05/28/2023]
Abstract
X-ray absorption spectra on the overdoped high-temperature superconductors Tl2Ba2CuO(6+delta) and La(2-x)SrxCuO(4+/-delta) reveal a striking departure in the electronic structure from that of the underdoped regime. The upper Hubbard band, identified with strong correlation effects, is not observed on the oxygen K edge, while the lowest-energy prepeak gains less intensity than expected above p approximately 0.21. This suggests a breakdown of the Zhang-Rice singlet approximation and a loss of correlation effects or a significant shift in the most fundamental parameters of the system, rendering single-band Hubbard models inapplicable. Such fundamental changes suggest that the overdoped regime may offer a distinct route to understanding in the cuprates.
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