Pseudogap, Superconducting Gap, and Fermi Arcs in Underdoped Cuprate Superconductors

摘要

Through the measurements of magnetic field dependence of specific heat in$La_{2-x}Sr_xCuO_4$ in zero temperature limit, we find that the nodal slope$v_\Delta$ of the superconducting gap has a very similar doping dependence ofthe pseudogap temperature $T^*$ or value $\Delta_p$. Meanwhile the maximumquasiparticle gap derived from $v_\Delta$ is quite close to $T^*$. Bothindicate a close relationship between the pseudogap and superconductivity. Itis also found that $T_c \approx \beta v_\Delta \gamma_n(0)$, where$\gamma_n(0)$ is the extracted zero temperature value of the normal statespecific heat coefficient which is proportional to the size of the residualFermi arc $k_{arc}$. These observations mimic the key predictions of the SU(2)slave boson theory based on the general resonating-valence-bond (RVB) picture.