Figure 1

(a) ${\chi }_{\text{2D}}^{\prime \prime }\left(\omega \right)$ for samples LSCZO(25,1)-B (at $T=5$ K), LSCZO(25,1)-A (at $T=10$ K), and LSCO($x=0.142$) (at $T=5$ K). Dashed lines are guides to the eye, and the inset shows the area of the magnetic Brillioun zone integrated. The solid black line denotes the expected response in ${\chi }_{\text{2D}}^{\prime \prime }\left(\omega \right)$ for Zn-free LSCO($x=0.25$) from Ref. 23. (b) Dispersion of IC spin excitations a distance $\delta$ from the (0.5, 0.5,0) position for $0\le E\le 15$ meV in both LSZO(25,1)-A and LSCZO(25,1)-B samples. The dashed line highlights the nearly dispersionless IC peak positions in the LSCO($x=0.142$) sample at $\delta =0.111\pm 0.001$ r.l. The dispersion spectrum was fit with a model of Gaussians symmetrically distributed about (0.5, 0.5, 0).Reuse & Permissions

Figure 2

Representative constant energy scans taken along the ($H$, 0.5, 0) direction in momentum space for the (a) LSCZO(25,1)-B and (b) LSCZO(25,1)-A samples. Both scans show preliminary hints of spectral weight centered at the (0.5, 0.5, 0) position and distinct from the expected IC peak positions. A constant energy scan at 6 meV showing the narrower IC peaks of LSCO($x=0.14$) with no spectral weight at (0.5, 0.5, 0) is overplotted as red squares in panel (a). Dashed circles highlight the appearance of this anomalous spectral weight at the commensurate AF wave vector.Reuse & Permissions

Figure 3

Spin fluctuations centered at the (0.5, 0.5, 0) AF wave vector in the LSCZO(25,1)-B sample. (a) Raw constant Q scans centered at (0.5, 0.5, 0) and background (0.63, 0.32, 0) positions collected at $T=5$ K. Inset shows the relative signal and background positions in reciprocal space. (b) Background subtracted spectra from panel (a) where symbols are (0.5, 0.5, 0)–(0.63, 0.32, 0) data. The solid line is the result of a simple Gaussian fit to the resulting mode centered at $E=6.4\pm 0.2$ meV. (c) Q scan taken at 6 meV through (0.5, 0.5, 0) taken along the [$H$, $-H$, 0] direction (direction shown in inset).Reuse & Permissions

Figure 4

Constant energy scans collected at $T=3$ K in the LSCZO(25,1)-B sample at various energies showing a central line-shape component centered at (0.5, 0.5, 0) in addition to the IC peak positions at (0.5 $\pm \delta$, 0.5, 0), (0.5, 0.5 $\pm \delta$, 0). Solid lines are the results of symmetric Gaussian fits to IC peak positions plus an additional Gaussian peak centered at the commensurate AF position. Dashed lines show the central Gaussian component on top of the nonmagnetic background (dash-dot lines). Solid brackets show the momentum resolution FWHM at (0.5, 0.5, 0) at each energy. Open squares in panel (a) are the results of a scan along $K$ while the solid circles are scans along $H$.Reuse & Permissions

Figure 5

(a) ${\chi }_{\text{2D}}^{\prime \prime }\left(\omega \right)$ in the LSCZO(25,1)-B sample with the contributions from the IC and commensurate line-shape components separated. The dashed line is a guide to the eye highlighting the peak in local spin susceptibility arising from the central AF mode in this Zn-doped sample. The solid line traces the nearly featureless ${\chi }_{\text{2D}}^{\prime \prime }\left(\omega \right)$ attributed to the IC excitations in this system. (b) Dispersion of IC spin excitations and the momentum line width of the central AF mode in LSCZO(25,1)-B. Reanalyzing the dispersion with the central AF peak qualitatively preserves the saddle-point feature in the spectrum where the half width at half maximum (HWHM) of the commensurate peak component is largest at the minimum incommensurability.Reuse & Permissions

Figure 6

(a) Phonon dispersion along the chemical cell zone boundary in sample LSCZO(25,1)-B. Constant Q scans are shown starting at (1, 0.5, 0) moving incrementally toward the expected IC magnetic peak position where the inset shows Q positions chosen for energy scans (crosses) relative to the IC magnetic positions (solid squares). (b) Dispersion of resulting phonon energies obtained from Lorentzian fits to the data in panel (a) overplotted with the dispersion of the IC magnetic peaks from both C5 and IN8 experiments on this same LSCZO(25,1)-B sample. Open squares show the deconvolved lifetime $\Gamma$ of the corresponding phonon mode as the dispersion approaches the branch of magnetic excitations. At the projected intersection, the lifetime of the phonon mode significantly broadens and the magnetic excitation spectrum broadens beyond the experimental resolution. Negative lifetime values result from an overly conservative deconvolution of the spectrometer resolution and should be regarded as resolution limited.Reuse & Permissions

Figure 7

Results of fits using an alternate model with a narrow momentum peak width at (0.5, 0.5, 0) as described in the text. (a) The resulting local spin susceptibility from fits using a constrained peak width at (0.5, 0.5, 0). Black circles show ${\chi }^{\prime \prime }\left(\omega \right)$ arising from the incommensurate peak component of the spectrum, while square symbols show ${\chi }^{\prime \prime }\left(\omega \right)$ arising from the Zn-induced commensurate mode. (b) Gaussian widths resulting from resolution convolved fits of both the incommensurate and commensurate peaks in Q space.Reuse & Permissions