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

Abstract

Through the measurements of magnetic field dependence of specific heat in $L{a}_{2-x}S{r}_{x}Cu{O}_4$ in zero temperature limit, we find that the nodal slope $v_{\Delta }$ of the superconducting gap has a very similar doping dependence of the pseudogap temperature $T^{\ast }$ or value ${\Delta }_p$. Meanwhile the maximum quasiparticle gap derived from $v_{\Delta }$ is quite close to $T^{\ast }$. Both indicate a close relationship between the pseudogap and superconductivity. It is 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 state specific heat coefficient which is proportional to the size of the residual Fermi 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.

4 pages, 3 figures, RevTeX4