Figure 1

Diagrams representing the low-energy magnetic fluctuations in La${}_{5/3}$Sr${}_{1/3}$NiO${}_4$, after Ref. 17. (a) Schematic map of the low-energy scattering in the $(h,k,0)$ plane of reciprocal space. Circles are stripe superlattice zone centers and diagonal lines indicate the diffuse scattering from ideal one-dimensional AFM spin chains running parallel to the charge stripes. Filled circles and full lines are for stripes running parallel to the $[1,\stackrel{̲}{1},0]$ direction; open circles and broken lines are for stripes parallel to the $[1,1,0]$ direction. (b) Model of AFM correlations along the charge stripes consistent with the observed q-1D diffuse scattering. The arrows indicate the instantaneous orientation of the spins on the charge stripes. For clarity, the background AFM order in the regions between the charge stripes is not shown.Reuse & Permissions

Figure 2

Maps of the scattering intensity in the $(h,k,0)$ reciprocal space plane of LSNO $(x=1/3)$. (a) Elastic scattering, (b) $E=2.5$ meV, and (c) $E=5$ meV. The data were collected on IN8 with a final wave vector of $k_f=2.662$ Å${}^{-1}$ at a temperature of 2 K. The contour plots are formed from $~$25$\times 30$ rectangular grids of data points. The data in (a) and (c) were measured with a pyrolytic graphite monochromator, and in (b) with a silicon monochromator. (d) Diagram of reciprocal space indicating the areas mapped out in (a)–(c).Reuse & Permissions

Figure 3

Neutron scattering from La${}_{2-x}$Sr${}_x$NiO${}_4$ ($x=0.275$) measured on MAPS. (a) Slice through the data volume averaged over the energy range 3–5 meV. (b) and (c) Cuts along the paths marked A and B in (a). An elastic scattering cut along path A is also displayed in (b). Solid and dashed lines indicate fits to the data with either one or two Gaussian peaks on a sloping background.Reuse & Permissions

Figure 4

Polarized neutron scattering from La${}_{2-x}$Sr${}_x$NiO${}_4$ ($x=0.275$). The scans are along the $(1,1,0)$ direction [path A in Fig. 3a] and measured at energies of 0 meV (elastic scattering, right scale) and 3 meV (left scale). Spin-flip (SF) and non-spin-flip (NSF) scattering channels are shown. The small peak in the NSF channel of the elastic scan is due to imperfect polarization, which has not been corrected for.Reuse & Permissions

Figure 5

Constant-energy scans along path B for the La${}_{2-x}$Sr${}_x$NiO${}_4$ ($x=1/3$) at 0.2 meV and 0.8 meV. The solid line is the best fit to a Gaussian function on a linear background.Reuse & Permissions

Figure 6

Line shape of the q-1D diffuse scattering in La${}_{2-x}$Sr${}_x$NiO${}_4$ ($x=1/3$) at low energy. The integrated intensities were obtained from the area of a Gaussian function fitted to a series of constant-energy scans like those shown in Fig. 5. For $E⩽0.6$ meV the signal was small and the Gaussian width was fixed in the fit to the value obtained from the $0.8$ meV data. The measurements were made with $k_f=1.2$ Å${}^{-1}$ for $E⩽1$ meV and $k_f=1.5$ Å${}^{-1}$ for $E⩾1$ meV, and normalized so as to match at $1$ meV. The solid line is calculated from Eq. (1) with $E_0=1.4$ meV, and the broken line is calculated with $E_0=0$. The inset shows the spectral weight function, which is related to the dynamical susceptibility by ${\chi }^{″}(\omega )\propto \omega F(\omega )$.Reuse & Permissions

Figure 7

Background-corrected energy scan of the q-1D diffuse scattering from La${}_{2-x}$Sr${}_x$NiO${}_4$ ($x=0.275$) at $\mathbf{Q}=(0.75,0.75,0)$. The background was estimated from energy scans at $(0.75,0.75,0)\pm (0.19,0.19,0)$. Inset: Constant-energy scans along path A at energies of 0.5 meV and 0.8 meV. Arrows indicate the positions of the spin-wave scattering from the AFM order of the Ni${}^{2+}$ spins and from the q-1D diffuse scattering. The 0.5 meV scan has been offset by the addition of 50 counts for clarity.Reuse & Permissions