Direct observation of bulk Fermi surface at higher Brillouin zones in a heavily hole-doped cuprate

We have observed the bulk Fermi surface (FS) in an overdoped ($x$=0.3) single crystal of La$_{2-x}$Sr$_x$CuO$_4$ by using Compton scattering. A 2-D momentum density reconstruction [1] from measured Compton profiles, yields a clear FS signature in a higher Brillouin zone centered at p=(1.5,1.5) a.u. The quantitative agreement with density functional theory (DFT) calculations [2] and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. We have also measured the 2-D angular correlation of positron annihilation radiation (2D-ACAR) [3] and noticed a similar quantitative agreement with the DFT simulations. However, 2D-ACAR does not give a clear signature of the FS in the extended momentum space in both theory and experiment. Work supported in part by the US DOE.\\ \mbox{[1]} Y. Tanaka \textit{et al.}, Phys. Rev. B {\bf 63}, 045120 (2001).\\ \mbox{[2]} S. Sahrakorpi \textit{et al.}, Phys. Rev. Lett. {\bf 95}, 157601 (2005).\\ \mbox{[3]} L. C. Smedskjaer \textit{et al.}, J. Phys. Chem. Solids {\bf 52}, 1541 (1991).