Incommensurate valence modulation in high-T-c cuprates

An incommensurate modulation has been observed in a Cn-rich La2CuO4.003 cry stal. It is shown that the modulation results from a periodically distribut ed holes lying on the CuO2 planes, and that the hole modulation may be rega rded to be a kind of valence modulation. It is shown that appreciable valen ce modulation contrast may be generated by the mechanisms of hole scatterin g alone when the period of the modulation is of the order of 2 nm. (C) 2000 Elsevier Science Ltd. All rights reserved.