Pseudogap, Superconducting Gap, and Fermi Arcs in Underdoped Cuprate Superconductors
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 $v_Δ$ of the superconducting gap has a very similar doping dependence of the pseudogap temperature $T^*$ or value $Δ_p$. Meanwhile the maximum quasiparticle gap derived from $v_Δ$ is quite close to $T^*$. Both indicate a close relationship between the pseudogap and superconductivity. It is also found that $T_c \approx βv_Δγ_n(0)$, where $γ_n(0)$ 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.