Study of anomalous temperature dependence of itinerant holes in under- and overdoped La 2− xSr xCuO 4 single crystals using polarised soft X-ray absorption spectroscopy

Abstract

Some experiments have recently shown that in the YBCO detwinned system charge aggregation takes place in the Cu–O 2 plane along the b-axis at T≫ T c followed by formation of Cooper pairs, again in the normal state. Polarised X-ray absorption measurements at the O K and Cu L 3 absorption edges in E∥ b orientation have been carried out on underdoped and overdoped single crystals of La 2−xSr x CuO 4 through a temperature range of 10–300 K to study the dependence of the itinerant hole density. Both the crystals do show an anomalous temperature dependence but there is a wide divergence in the earlier and our results. This paper discusses the results and possible causes for the difference.