Upper critical field and specific heat of cuprates

作者：Kabanov VV^*; Zavaritsky VN; Alexandrov AS

来源：Journal of Superconductivity, 2004, 17(1): 113-116.

DOI：10.1023/B:JOSC.0000011852.01205.7f

• superconductivity
• critical field
• Bose gas

A representative set of magnetotransport measurements in novel superconductors is analyzed. The resistive upper critical field, H-c2(T) of many cuprates, of superconducting spin-ladders, and organic (TMTSF)2X systems has a universal nonlinear temperature dependence H-c2 proportional to (T-c-T)(3/2) in a wide temperature interval near T-c, while its low-temperature behavior depends on the chemical formula and sample quality. The unusual H-c2(T) is described as the Bose-Einstein condensation field of preformed pairs. Its universal temperature dependence follows from the scaling arguments. Controversy in the determination of H-c2(T) from the resistivity and specific heat measurements is resolved in the framework of the charged Bose-gas model with the impurity scattering. It is shown that specific heat shows two anomalies. The high-temperature anomaly is strong and shows only weak shift with applied field. The low-temperature anomaly corresponds to resistive transition and is very weak in agreement with the experiments. Both anomalies coincide at H=0.

• 出版日期2004-2