u‰‰ŽาF Kโ@—Sถ Ži—Œคj “๚ŽžF ‚UŒŽ@‚Q‚Q“๚i‹เj@Œ฿Œใ‚SŽž‚R‚O•ช‚ฉ‚็ ๊ŠF ยŽRŠw‰@‘ๅŠw@—HŠw•”i‘Š–อŒดƒLƒƒƒ“ƒpƒXj‚k“‚UŠK@‚k‚U‚O‚RŽบ ‘่–ฺF uAn Intrinsic Cu-O-Cu Bond-centered Electronic Glass with Disperse 4a0-wide Unidirectional Domains in Strongly Underdoped Cupratesv —vŽ|F Doping holes into the CuO2 charge transfer insulator alters the electronic correlation, leading to the high-temperature superconductivity (HTS). The electronic evolution is accompanied by spectral weight transfer from the high energy states of the insulator to low energies. Recently, it has been proposed [1,2] that these effects might be observable as an asymmetry of electron tunneling currents (tunneling asymmetry; TA) with bias voltage across the chemical potential. Atomic-scale TA-phenomena would then be of crucial importance to understand the fundamental electronic structure of the CuO2 plane from whence the HTS emerges. In this talk, we will show the first application of atomic resolution TA-imaging by a scanning tunneling microscope, detecting virtually identical phenomena in two different lightly hole-doped cuprates [3]. We find intense spatial variation primarily on planer oxygen sites. Their spatial arrangements appear to be a Cu-O-Cu bond-centered electronic glass, breaking translational symmetry of lattice and 90o-rotational symmetry. 4a0-wide unidirectional domains (a0: Cu-O-Cu length) are embedded throughout this matrix and running along the both Cu-O bonds without preferred orientation. Relationship to the electronic cluster glass, the bond-centered stripe, and the HTS will be discussed. This work is done in collaboration with C. Taylor, A. Schmidt, C. Lupien, T. Hanaguri, M.Azuma, M. Takano, K. Fujita, H. Eisaki, H. Takagi, S. Uchida, and J. C. Davis. [1] P. W. Anderson, N. P. Ong, cond-mat/0405518 and J. Phys. Chem. Solid 67, 1 (2006). [2] M. Randeria, R. Sensarma, N. Trivedi, F. -C. Zhang, Phys. Rev. Lett. 95, 137001(2005). [3] Y. Kohsaka et al., Science 315, 1380 (2007). --------------------------------- ‹ครF@ยŽRŠw‰@‘ๅŠw@—HŠw‰๏