  Insulating La1.95Sr0.05CuO4 shares with superconducting cuprates the same
Fincher-Burke-like spin excitations, which usually are observed in itinerant
antiferromagnets. The local spectral function satisfies omega/T scaling above
~16 K for this incommensurate insulating cuprate. Together with previous
results in commensurate insulating and incommensurate superconducting cuprates,
these results further support the general scaling prediction for square-lattice
quantum spin S=1/2 systems. The width of incommensurate peaks in
La1.95Sr0.05CuO4 scales to a similar finite value as at optimal doping,
strongly suggesting that they are similarly distant from a quantum critical
point. They might both be limited to a finite correlation length by the partial
spin-glass freezing.
