Temperature dependence of the hole density in high-T(C) superconductors Bi(2-y)Pb(y)Sr(2)CaCu(2)O(8+ delta )

• Published in: Physica. C, Superconductivity Vol. 485; pp. 163 - 167
• Main Authors: Ghafari, A, Janowitz, C, Ariffin, A K, Dwelk, H, Krapf, A, Manzke, R
• Format: Journal Article
• Language: English
• Published: 14-02-2013
• Subjects: Atomic properties; COPPER OXIDE; DENSITY; Hole density; HOLES; MATHEMATICAL ANALYSIS; Mathematical models; Optimization; PROPERTIES; SINGLE CRYSTALS; SUPERCONDUCTIVITY; SUPERCONDUCTORS; Temperature dependence; Two fluid models; X RAYS
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2012.11.007

One of the most puzzling anomalies of high-T(C) cuprates is the strong temperature dependence of the Hall coefficient (R(H)) and the hole density (n(H)). Gor'kov and Teitel'baum (GT) proposed by using experimental data of La(2-x)Sr(x)CuO(4) (LSCO) a two fluid model. The number of holes per Cu atom n(H), changes with temperature according to n(H)(T,x)=n(0)(x) + n(1)(x)exp(- Delta (x)/T) [1]. To clarify the temperature dependence of n(H) we have determined nH from X-ray absorption spectra (XAS) at the CuL(3) edge for nearly optimum and slightly underdoped Bi(2-y)Pb(y)Sr(2)CaCu(2)O(8+ delta ) single crystals yielding directly the absolute value of n(H) in the CuO(2) planes and also its change with temperature n(H)(T). It shows pronounced structures between 10 K and 300 K. The temperature dependence puts constraints to the applicability of previously developed models: (i) the two-band model without any explicit temperature dependence and (ii) the formula of GT, because the latter is not able to fit our data over the whole temperature range from 10 K to 300 K. Instead the thermal behavior of n(H) proposes a function with at least three terms, i.e. a third term added to the formula of GT is of exponential form ~T(3'2).