Low-energy antiferromagnetic spin fluctuations limit the coherent superconducting gap in cuprates
Low-energy antiferromagnetic spin fluctuations limit the coherent superconducting gap in cuprates
Motivated by recent attention to a potential antiferromagnetic quantum critical point at $x_c\sim 0.19$, we have used inelastic neutron scattering to investigate the low-energy spin excitations in crystals of La$_{2-x}$Sr$_x$CuO$_4$ bracketing $x_c$. We observe a peak in the normal-state spin-fluctuation weight at $\sim20$~meV for both $x=0.21$ and 0.17, inconsistent with …