Thermodynamic and other properties of La1.85Sr0.15CuO4

Abstract

We have calculated the thermodynamic, electromagnetic, and critical-field properties of superconducting ${\mathrm{La}}_{1.85}$ ${\mathrm{Sr}}_{0.15}$Cu${\mathrm{O}}_4$, using the electron-phonon spectral density determined recently by Weber, from band-structure calculations. Even though the electron-phonon mass enhancement is $\lambda =2.6\mathrm{}$, the predicted dimensionless ratios are not very different from those of Pb. For example, the normalized specific-heat jump at $T_c$, $\frac{\Delta C}{\gamma \mathrm{}\left(0\right)\mathrm{}{T}_c}=2.8\mathrm{}$, the ratio of twice the energy gap to $T_c$, $\frac{2{\Delta }_0}{k_B{T}_c}=5.3\mathrm{}$ and $\frac{\gamma \mathrm{}\left(0\right)\mathrm{}{T}_c^2}{H_c^2\mathrm{}\left(0\right)\mathrm{}}=0.124\mathrm{}$ where $H_c\mathrm{}\left(0\right)\mathrm{}$ is the zero-temperature ($T$) thermodynamic critical field. The reduced upper critical field $h_{c2\mathrm{}}\mathrm{}\left(0\right)\mathrm{}$ at $T=0\mathrm{}$ in the dirty limit equals 0.76 and shows little Pauli limiting in calculations with $H_{c2\mathrm{}}\mathrm{}\left(0\right)\mathrm{}\simeq 43$ T.