J. A. Rosen, R. Comin, G. Levy, D. Fournier, Z. -H. Zhu, B. Ludbrook, C. N. Veenstra, A. Nicolaou, D. Wong, P. Dosanjh, Y. Yoshida, H. Eisaki, G. R. Blake, F. White, T. T. M. Palstra, R. Sutarto, F. He, A. Frano, Y. Lu, B. Keimer, G. A. Sawatzky, L. Petaccia, A. Damascelli
Neutron and x-ray scattering experiments have provided mounting evidence for spin and charge ordering phenomena in underdoped cuprates. These range from early work on stripe correlations in Nd-LSCO to the latest discovery of charge-density-waves in YBCO. Both phenomena are characterized by a pronounced dependence on doping, temperature, and an externally applied magnetic field. Here we show that these electron-lattice instabilities exhibit also a previously unrecognized bulk-surface dichotomy. Surface-sensitive electronic and structural probes uncover a temperature-dependent evolution of the CuO2 plane band dispersion and apparent Fermi pockets in underdoped Bi2201, which is directly associated with an hitherto-undetected strong temperature dependence of the incommensurate superstructure periodicity below 130K. In stark contrast, the structural modulation revealed by bulk-sensitive probes is temperature independent. These findings point to a surface-enhanced incipient charge-density-wave instability, driven by Fermi surface nesting. This discovery is of critical importance in the interpretation of single-particle spectroscopy data and establishes the surface of cuprates and other complex oxides as a rich playground for the study of electronically soft phases.
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http://arxiv.org/abs/1111.2673
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