# The Fincher-Burke spin excitations and omega/T scaling in the insulating 5% Sr-doped La2CuO4

## TL;DR

This study reveals that insulating La1.95Sr0.05CuO4 exhibits Fincher-Burke-like spin excitations and omega/T scaling similar to superconducting cuprates, indicating common underlying quantum spin dynamics.

## Contribution

It demonstrates omega/T scaling and Fincher-Burke-like excitations in an insulating cuprate, extending the understanding of quantum spin behavior across different doping levels.

## Key findings

- Omega/T scaling observed above ~16 K in La1.95Sr0.05CuO4.
- Incommensurate peak widths scale similarly to optimally doped cuprates.
- Results support universal quantum spin scaling in square-lattice S=1/2 systems.

## Abstract

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.