LSCO magnetic excitations: persistence within a measured window

Dean and colleagues find broadened magnetic excitations in LSCO up to $x=0.40$. Their reported fitted window is $\mathbf Q=(0.18\text{–}0.40,0)$ in reciprocal lattice units. It complements neutron measurements near $(0.5,0.5)$. Similar dispersion and comparable integrated intensity in this window do not establish conservation across the whole Brillouin zone.

The resolution is 130 meV HWHM, not FWHM. Fits include a thermal factor and resolution convolution. Unresolved phonon/multispin scattering contributes an estimated 15% overestimate to width and intensity. Supplementary intensity corrections include a changed incident flux and a 0.78 factor for the nominally thicker films; instrumental instability enters the uncertainty.

The main-text grouping assigns approximately 53 nm to $x=0.16$ and 99 nm to $x=0.26$. Supplementary Table I instead lists $97\pm3$ nm and $52\pm3$ nm, respectively. The normalization discussion follows the former grouping. These records are not reconciled here; the corrected intensities have not been independently reproduced.

The quoted 27% spectral fraction comes from an undoped spin-wave calculation. Extending its persistence with doping assumes comparable scaling along an unmeasured diagonal direction.

Editorially, persistence of an excitation is one constraint on a pairing theory. It cannot by itself select a unique interaction or explain the transition temperature. Compare the relevant momentum, energy and sample conditions, rather than treating an integrated signal as a complete pairing kernel.

This note covers study 3. Interface localization covers studies 2 and 9; THz conductivity covers study 5. Six studies and additional cross-topic comparisons remain pending.

Each source keeps its own uncertainty and access limits. The source-note merge remains partial; a linked paper does not mean every claim has been independently reviewed.